CA2303234A1 - Zero power power-on-reset circuit - Google Patents
Zero power power-on-reset circuit Download PDFInfo
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- CA2303234A1 CA2303234A1 CA002303234A CA2303234A CA2303234A1 CA 2303234 A1 CA2303234 A1 CA 2303234A1 CA 002303234 A CA002303234 A CA 002303234A CA 2303234 A CA2303234 A CA 2303234A CA 2303234 A1 CA2303234 A1 CA 2303234A1
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/22—Modifications for ensuring a predetermined initial state when the supply voltage has been applied
- H03K17/223—Modifications for ensuring a predetermined initial state when the supply voltage has been applied in field-effect transistor switches
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
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- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
A power-on-reset circuit includes a first charging stage (162) for building up a charge during power up. The rising voltage of the first charging stage is sensed and used to control means (122) for charging up a second charging stage (164). When the second charging stage reaches a first voltage level, a circuit (130) is tripped to pull the potential of the first to ground. The grounding of the first charging stage (162) is fed back to the charging means (122) which shuts off its power burning components and maintains the first voltage level at the second charging stage (164).
Description
Description ZERO POWER POWER-ON-RESET CIRCUIT
TECHNICAL FIELD
The present invention relates to power-on reset circuits and more specifically to power-on reset circuits used in semiconductor devices.
BACKGROUND ART
When power (V~) is applied to a semiconductor device, the various components comprising the device receive power in an essentially random fashion. One potential outcome is an indeterminate state when Vac reaches a steady-state level. Similarly, some components such as flip-flops require a settling time for the components to reach a steady operating condition. Thus a circuit, referred to as a power-on reset (POR) circuit, is employed to ensure that the components of a semiconductor device remain in a reset state until a stable V~~ is attained. The POR holds the device components in reset with a reset signal which is removed when steady state conditions are attained.
With increasing use of laptop computers, personal digital devices such as PDAs, cell phones and so on, there is an increased awareness to maintaining a low power consumption. A prime area of consideration is the design of POR circuits. Such circuits come into play only during the power-on cycle, and ideally become inactive and consume no power afterward. It is thus desirable to have a POR circuit that is capable of turning itself off in order to conserve power during its inactive (or steady state) condition.
SUMMARY OF THE INVENTION
A power-on reset circuit comprises a first charging means coupled between a power supply terminal and a node A. The potential at node A drives a first circuit consisting of first and second series coupled transistors, having an output which follows the potential - WO 99/27652 pCT/US98/24630 at node A. The output is coupled to a second circuit consisting of third and fourth transistors, having an output which charges a capacitor coupled between the input of the inverter and ground, thus completing a feedback circuit to node A. The second circuit responds to the output of the first circuit by delaying for a period of time before actually charging the capacitor.
In a preferred embodiment, the charging means is a capacitor coupled between the power supply terminal and node A. The transistors of the first circuit are N-channel zero threshold devices. The transistors in the second circuit include a P-channel device and an N-channel device, the N-channel device also being a zero threshold voltage device.
BRIEF DESCRIPTION OF THE DRAWING
The Figure shows a schematic diagram of the POR
circuit of the present invention.
BEST MODE OF CARRYING OUT THE INVENTION
With reference to the Figure, the power-on reset circuit 100 of the present invention comprises two outputs POR and POR, respectively providing a reset signal and an active low reset signal at the front end of circuit 100. The POR signal is driven by inverters 106 and 102, and the POR signal is driven by inverter 104 which simply inverts the output of inverter 102. The width-to-length (W/L) ratios of the transistors comprising each inverter are given. The top ratio specifies the device dimensions for the P-channel device, while the bottom ratio specifies the dimensions for the N-channel device. This is exemplified in the Figure by the internal representation of inverter 130, showing the transistors and their corresponding W/L ratios. In addition to the inverters, the W/L ratios of the transis tore comprising the circuit are also shown in the Figure.
The back end of the power-on reset circuit includes a voltage detection stage 162 comprising - WO 99/~?652 PCT/US98/24630 N-channel transistor 150 having a source-drain coupling between a power rail 110 and a node B. N-channel transistor 152 has a similar source-drain coupling between node B and ground. Each N-channel transistor 150, 152 is a zero threshold voltage (Vt = 0 V) device.
Moving forward, node B is coupled to the gates of transistors 140 and 142 which constitute charging circuit 164. Transistor 140 is a P-channel device having a source coupled to power rail 110 and a drain coupled to the drain of an N-channel, zero threshold voltage transistor 142. The source of transistor 142 is coupled to ground.
Continuing forward, the drain-drain connection node C of the 140/142 transistor pair is coupled to the input to inverter 130. Node C is also coupled to ground via capacitor 122. The output of inverter 130 is coupled to node A which in turn is coupled to power rail 110 via capacitor 120. A feedback path 160 is provided from node A to drive the gates of transistors 150 and 152.
In operation, when power is initially applied to the circuit, power rail 110 begins camping up from zero volts. The voltage V~ at node A follows the voltage Vpower rat t at power rail 110 as capacitor 120 begins to charge. As V~ increases above 0 V, transistors 150, 152 begin to turn on. Since the gate of transistor 152 is coupled to node A, it immediately begins to conduct, recalling that transistor 152 has a source coupled to ground and Vt = 0 V, and will continue to do so during the power-up sequence since the condition V~ >_ 0 V holds during power-up. This has the effect of lowering the potential VB of node B to ground potential. Consequently, transistor 150 begins to turn on, since its V~$ too is greater than Vt = 0 V. This tends to drive VB from ground potential to V~r rai l ~ However, the gate-source capacitance of transistor 142 is large; observe in the Figure that the W/L ratio for transistor 142 is 3.1/117.
This has the effect of delaying the rise of Ve and, as a result, VB will lag behind V~r r.it ~
- wo ~m6sz rc~nus9sn4~o Continuing with the next stage, if VB lags behind V~r rail bY a sufficient amount, P-channel transistor 140 will begin to turn on, thus allowing a charge to accumulate on capacitor 122. As VB continues to rise, transistor 142 begins to turn on, since its Vt = 0 v and Ve is positive. This will tend to slow the charge time of capacitor 122 as the charge flowing from transistor 140 is divided between capacitor 122 and transistor 142. As the capacitor charges, the voltage V~
at node C begins to rise. V~ continues to rise until it reaches the trip point of inverter 130, namely the threshold voltage of the N-channel device comprising the inverter. When that happens node A is coupled to ground via the N-channel device of inverter 130, thus taking the voltage V~ at node A to ground.
As a consequence, the gate potential of transistors 150, 152 go to ground because of the feedback path 160 from node A to the gates of the transistors.
Since VB is positive at this point, the effect of grounding the gate of transistor 150 is to turn the transistor off, since its V~s becomes lass than the transistor's threshold voltage. However, transistor 152 remains on, since V~8 = 0 V and its Vt is 0 V. This combination of circumstances tends to drive VB to ground potential. Though VB goes to ground, transistor 150 remains off even though the gate potential is at 0 V and VB is at 0 V. Any tendency for transistor 150 to turn on will drive Vs above the transistor's gate potential, which remains at 0 V by virtue of the feedback path 160 to node A, and thus turn itself off (recall that Vt = 0 V). VB is driven back to ground through transistor 152 and in this way, VB is maintained at ground potential.
P-channel transistor 140 remains turned on since V~ = VB - V~r rail ~ which at this point is less than the transistor's Vt. Capacitor 122 maintains its charge via transistor 140, thus maintaining a HI at the input of inverter 130 and producing a constant LO (i.e. ground) at its output. Thus node A remains grounded. Consequently, - wo ~m6sz rc~rius9gn463o transistors 150, 152 are maintained in their current state (via feedback path 160): i.e. transistor 152 is turned on (because V~ = Vt = 0 V) and transistor 150 remains off since any tendency for the transistor to turn on will be counteracted by the rising of Vg above its gate potential. With Va maintained at ground potential, transistor 140 remains on and transistor 142 is off.
This condition presents a logic HI to inverter 130 which outputs a LO, thus holding node A to ground.
~ Thus, in the steady state condition, it can be seen that there are no power burning stages. Transistor 152 remains on to hold node B at ground potential, and since transistor 150 is off there is no current flow from the power supply through transistor 152. Transistor 140 serves to provide a logic HI to inverter 130, thus maintaining a LO at node A, which is fed back to transistor 152 and so on, maintaining the steady state condition. Capacitor 120 and capacitor 122 maintains its charged state since there is no discharge path and so does not dissipate energy in the steady state condition.
As noted above, the triggering of inverter 130 drives node A to ground thus putting the circuit into a zero power-consuming steady-state condition. There are two factors which affect the triggering of inverter 130.
First, is the charge build up of capacitor 122. It is the charging of the capacitor which brings V~ up to a positive voltage. The charge time of capacitor 122 can be adjusted so that the trip point of inverter 130 is not reached until the power reaches the desired voltage level V~~. As shown in the Figure, a value of 2.2226 pF for capacitor 122 was shown to exhibit the desired effect.
The second factor is the sizing of N-channel transistor 142. The high ground-source capacitance resulting from the large gate area of the transistor (W/L
is 3.1/117) permits VB to lag behind V~r rait ~ i"loreover, VB must be at a potential sufficiently lower than V~r rail so that V~8 of P-channel transistor 140 becomes less than its threshold voltage, allowing transistor 140 to turn on - wo 99m6sZ pcT~s9sn~o to charge capacitor 122. Using known simulation and design techniques, it was determined that a W/L ratio of 3.1/117 was adequate.
TECHNICAL FIELD
The present invention relates to power-on reset circuits and more specifically to power-on reset circuits used in semiconductor devices.
BACKGROUND ART
When power (V~) is applied to a semiconductor device, the various components comprising the device receive power in an essentially random fashion. One potential outcome is an indeterminate state when Vac reaches a steady-state level. Similarly, some components such as flip-flops require a settling time for the components to reach a steady operating condition. Thus a circuit, referred to as a power-on reset (POR) circuit, is employed to ensure that the components of a semiconductor device remain in a reset state until a stable V~~ is attained. The POR holds the device components in reset with a reset signal which is removed when steady state conditions are attained.
With increasing use of laptop computers, personal digital devices such as PDAs, cell phones and so on, there is an increased awareness to maintaining a low power consumption. A prime area of consideration is the design of POR circuits. Such circuits come into play only during the power-on cycle, and ideally become inactive and consume no power afterward. It is thus desirable to have a POR circuit that is capable of turning itself off in order to conserve power during its inactive (or steady state) condition.
SUMMARY OF THE INVENTION
A power-on reset circuit comprises a first charging means coupled between a power supply terminal and a node A. The potential at node A drives a first circuit consisting of first and second series coupled transistors, having an output which follows the potential - WO 99/27652 pCT/US98/24630 at node A. The output is coupled to a second circuit consisting of third and fourth transistors, having an output which charges a capacitor coupled between the input of the inverter and ground, thus completing a feedback circuit to node A. The second circuit responds to the output of the first circuit by delaying for a period of time before actually charging the capacitor.
In a preferred embodiment, the charging means is a capacitor coupled between the power supply terminal and node A. The transistors of the first circuit are N-channel zero threshold devices. The transistors in the second circuit include a P-channel device and an N-channel device, the N-channel device also being a zero threshold voltage device.
BRIEF DESCRIPTION OF THE DRAWING
The Figure shows a schematic diagram of the POR
circuit of the present invention.
BEST MODE OF CARRYING OUT THE INVENTION
With reference to the Figure, the power-on reset circuit 100 of the present invention comprises two outputs POR and POR, respectively providing a reset signal and an active low reset signal at the front end of circuit 100. The POR signal is driven by inverters 106 and 102, and the POR signal is driven by inverter 104 which simply inverts the output of inverter 102. The width-to-length (W/L) ratios of the transistors comprising each inverter are given. The top ratio specifies the device dimensions for the P-channel device, while the bottom ratio specifies the dimensions for the N-channel device. This is exemplified in the Figure by the internal representation of inverter 130, showing the transistors and their corresponding W/L ratios. In addition to the inverters, the W/L ratios of the transis tore comprising the circuit are also shown in the Figure.
The back end of the power-on reset circuit includes a voltage detection stage 162 comprising - WO 99/~?652 PCT/US98/24630 N-channel transistor 150 having a source-drain coupling between a power rail 110 and a node B. N-channel transistor 152 has a similar source-drain coupling between node B and ground. Each N-channel transistor 150, 152 is a zero threshold voltage (Vt = 0 V) device.
Moving forward, node B is coupled to the gates of transistors 140 and 142 which constitute charging circuit 164. Transistor 140 is a P-channel device having a source coupled to power rail 110 and a drain coupled to the drain of an N-channel, zero threshold voltage transistor 142. The source of transistor 142 is coupled to ground.
Continuing forward, the drain-drain connection node C of the 140/142 transistor pair is coupled to the input to inverter 130. Node C is also coupled to ground via capacitor 122. The output of inverter 130 is coupled to node A which in turn is coupled to power rail 110 via capacitor 120. A feedback path 160 is provided from node A to drive the gates of transistors 150 and 152.
In operation, when power is initially applied to the circuit, power rail 110 begins camping up from zero volts. The voltage V~ at node A follows the voltage Vpower rat t at power rail 110 as capacitor 120 begins to charge. As V~ increases above 0 V, transistors 150, 152 begin to turn on. Since the gate of transistor 152 is coupled to node A, it immediately begins to conduct, recalling that transistor 152 has a source coupled to ground and Vt = 0 V, and will continue to do so during the power-up sequence since the condition V~ >_ 0 V holds during power-up. This has the effect of lowering the potential VB of node B to ground potential. Consequently, transistor 150 begins to turn on, since its V~$ too is greater than Vt = 0 V. This tends to drive VB from ground potential to V~r rai l ~ However, the gate-source capacitance of transistor 142 is large; observe in the Figure that the W/L ratio for transistor 142 is 3.1/117.
This has the effect of delaying the rise of Ve and, as a result, VB will lag behind V~r r.it ~
- wo ~m6sz rc~nus9sn4~o Continuing with the next stage, if VB lags behind V~r rail bY a sufficient amount, P-channel transistor 140 will begin to turn on, thus allowing a charge to accumulate on capacitor 122. As VB continues to rise, transistor 142 begins to turn on, since its Vt = 0 v and Ve is positive. This will tend to slow the charge time of capacitor 122 as the charge flowing from transistor 140 is divided between capacitor 122 and transistor 142. As the capacitor charges, the voltage V~
at node C begins to rise. V~ continues to rise until it reaches the trip point of inverter 130, namely the threshold voltage of the N-channel device comprising the inverter. When that happens node A is coupled to ground via the N-channel device of inverter 130, thus taking the voltage V~ at node A to ground.
As a consequence, the gate potential of transistors 150, 152 go to ground because of the feedback path 160 from node A to the gates of the transistors.
Since VB is positive at this point, the effect of grounding the gate of transistor 150 is to turn the transistor off, since its V~s becomes lass than the transistor's threshold voltage. However, transistor 152 remains on, since V~8 = 0 V and its Vt is 0 V. This combination of circumstances tends to drive VB to ground potential. Though VB goes to ground, transistor 150 remains off even though the gate potential is at 0 V and VB is at 0 V. Any tendency for transistor 150 to turn on will drive Vs above the transistor's gate potential, which remains at 0 V by virtue of the feedback path 160 to node A, and thus turn itself off (recall that Vt = 0 V). VB is driven back to ground through transistor 152 and in this way, VB is maintained at ground potential.
P-channel transistor 140 remains turned on since V~ = VB - V~r rail ~ which at this point is less than the transistor's Vt. Capacitor 122 maintains its charge via transistor 140, thus maintaining a HI at the input of inverter 130 and producing a constant LO (i.e. ground) at its output. Thus node A remains grounded. Consequently, - wo ~m6sz rc~rius9gn463o transistors 150, 152 are maintained in their current state (via feedback path 160): i.e. transistor 152 is turned on (because V~ = Vt = 0 V) and transistor 150 remains off since any tendency for the transistor to turn on will be counteracted by the rising of Vg above its gate potential. With Va maintained at ground potential, transistor 140 remains on and transistor 142 is off.
This condition presents a logic HI to inverter 130 which outputs a LO, thus holding node A to ground.
~ Thus, in the steady state condition, it can be seen that there are no power burning stages. Transistor 152 remains on to hold node B at ground potential, and since transistor 150 is off there is no current flow from the power supply through transistor 152. Transistor 140 serves to provide a logic HI to inverter 130, thus maintaining a LO at node A, which is fed back to transistor 152 and so on, maintaining the steady state condition. Capacitor 120 and capacitor 122 maintains its charged state since there is no discharge path and so does not dissipate energy in the steady state condition.
As noted above, the triggering of inverter 130 drives node A to ground thus putting the circuit into a zero power-consuming steady-state condition. There are two factors which affect the triggering of inverter 130.
First, is the charge build up of capacitor 122. It is the charging of the capacitor which brings V~ up to a positive voltage. The charge time of capacitor 122 can be adjusted so that the trip point of inverter 130 is not reached until the power reaches the desired voltage level V~~. As shown in the Figure, a value of 2.2226 pF for capacitor 122 was shown to exhibit the desired effect.
The second factor is the sizing of N-channel transistor 142. The high ground-source capacitance resulting from the large gate area of the transistor (W/L
is 3.1/117) permits VB to lag behind V~r rait ~ i"loreover, VB must be at a potential sufficiently lower than V~r rail so that V~8 of P-channel transistor 140 becomes less than its threshold voltage, allowing transistor 140 to turn on - wo 99m6sZ pcT~s9sn~o to charge capacitor 122. Using known simulation and design techniques, it was determined that a W/L ratio of 3.1/117 was adequate.
Claims (29)
1. A power-on reset circuit comprising:
charging means (120) for outputting a voltage level in response to a rising power supply voltage:
first means (130), electrically coupled to the charging means, for providing a ground potential in response to a trigger signal, the first means adapted to hold the voltage level of the charging means at ground potential when triggered; and second means (162, 164, 122), electrically coupled to the first means, for providing a trigger signal in response to a rising voltage level at the charging means, the second means adapted to trigger the first means, the second means including a pair of series-coupled zero voltage threshold transistors (150, 152):
a feedback path coupling the charging means (120) to the pair of zero voltage threshold transistors (122).
charging means (120) for outputting a voltage level in response to a rising power supply voltage:
first means (130), electrically coupled to the charging means, for providing a ground potential in response to a trigger signal, the first means adapted to hold the voltage level of the charging means at ground potential when triggered; and second means (162, 164, 122), electrically coupled to the first means, for providing a trigger signal in response to a rising voltage level at the charging means, the second means adapted to trigger the first means, the second means including a pair of series-coupled zero voltage threshold transistors (150, 152):
a feedback path coupling the charging means (120) to the pair of zero voltage threshold transistors (122).
2. The reset circuit of claim 1 wherein the charging means is a first capacitor (120) coupled between the power supply voltage and a first node (A), thereby producing a rising voltage level as a power supply begins to increase in voltage.
3. The reset circuit of claim 2 wherein the first means is an inverter (130) having an input to receive the trigger signal and having an output coupled to the first node (A).
4. The reset circuit of claim 3 wherein the second means includes a second capacitor (122) coupled between the inverter input and ground, the trigger signal being a first voltage potential across the second capacitor.
5. The reset circuit of claim 4 wherein the second means further includes a circuit (164) for charging the second capacitor (122) to a level equal to the first voltage potential, in response to the rising voltage level of the charging means.
6. The reset circuit of claim 3 wherein the second means further includes:
a second capacitor (122) coupled between the inverter input and ground; and a P-channel device (140) coupled in series with an N-channel device (142) at a second node (C), the second node being coupled to the second capacitor to be charged thereby;
the pair of zero voltage threshold transistors (150, 152) coupled at a third node, the third (B) node being coupled to the gates of the P-channel and the N-channel devices;
the feedback path (160) coupling the first node to the gate of each of the zero voltage threshold transistors.
a second capacitor (122) coupled between the inverter input and ground; and a P-channel device (140) coupled in series with an N-channel device (142) at a second node (C), the second node being coupled to the second capacitor to be charged thereby;
the pair of zero voltage threshold transistors (150, 152) coupled at a third node, the third (B) node being coupled to the gates of the P-channel and the N-channel devices;
the feedback path (160) coupling the first node to the gate of each of the zero voltage threshold transistors.
7. The reset circuit of claim 6 wherein the N-channel device (142) is a zero threshold voltage device.
8. A power-on reset circuit comprising:
first means for raising the potential at a node A as a power supply voltage increases second means (150, 152), electrically coupled to node A, for raising the potential at a second node B
in response to a rising potential at node A, the second means including first and second series-coupled, N-channel transistors, coupled at node B, gates of the N-channel transistors coupled to node A;
third means (140), electrically coupled to node B, for raising the potential at a third node C in response to a rising potential at node B, the third means having means for delaying the onset of raising the potential at node C; and fourth means (130) for holding the potential at node A to ground in response to node C reaching a first voltage level, the fourth means having an input electrically coupled to node C to receive the potential at node C, the fourth means further having an output electrically coupled to node A.
first means for raising the potential at a node A as a power supply voltage increases second means (150, 152), electrically coupled to node A, for raising the potential at a second node B
in response to a rising potential at node A, the second means including first and second series-coupled, N-channel transistors, coupled at node B, gates of the N-channel transistors coupled to node A;
third means (140), electrically coupled to node B, for raising the potential at a third node C in response to a rising potential at node B, the third means having means for delaying the onset of raising the potential at node C; and fourth means (130) for holding the potential at node A to ground in response to node C reaching a first voltage level, the fourth means having an input electrically coupled to node C to receive the potential at node C, the fourth means further having an output electrically coupled to node A.
9. The reset circuit of claim 8 further including an inverter (106) having an input coupled to node A, an output of the inverter providing a reset signal.
10. The reset circuit of claim 8 wherein the fourth means is an inverter (130) and the first voltage level is the trip point of the inverter.
11. The reset circuit of claim 8 further including a power supply terminal and a ground terminal, wherein the first means is a first capacitor (120) coupled between the power supply and ground terminals.
12. [Cancelled]
13. The reset circuit of claim 8 wherein the N-channel transistors are zero threshold voltage devices.
14. The reset circuit of claim 8 wherein the third means is a P-channel transistor having source and drain terminals coupled between the power supply terminal and node C, and having a gate coupled to node B.
15. The reset circuit of claim 14 wherein the means for delaying is an N-channel, zero threshold voltage device (140) having drain and source terminals coupled between node C and ground, and having a gate coupled to node B.
16. The reset circuit of claim 15 wherein the third means further includes a second capacitor (122) coupled between node C and ground.
17. The reset circuit of claim 14 wherein the first and second N-channel transistors (150, 152) are zero threshold voltage devices.
18. A power-on reset circuit comprising:
a first terminal (110) for connection to a first potential:
a second terminal for connection to a second potential;
a first capacitor (120) coupled between the first terminal and a first node;
an inverter (130) having an input and an output, the output coupled to the first node;
a second capacitor (122) coupled between the input of the inverter and the second terminal;
first means (162), electrically coupled to the first node (110), for outputting a voltage level that follows the potential of the first node, the first means including a pair of series-connected N-channel transistors coupled between the first and second terminals, a gate of each of the transistors being coupled to the first node; and second means (164) for charging the second capacitor (122), the second means having an input coupled to receive the output voltage of the first means, the second means further having an output coupled to the second capacitor.
a first terminal (110) for connection to a first potential:
a second terminal for connection to a second potential;
a first capacitor (120) coupled between the first terminal and a first node;
an inverter (130) having an input and an output, the output coupled to the first node;
a second capacitor (122) coupled between the input of the inverter and the second terminal;
first means (162), electrically coupled to the first node (110), for outputting a voltage level that follows the potential of the first node, the first means including a pair of series-connected N-channel transistors coupled between the first and second terminals, a gate of each of the transistors being coupled to the first node; and second means (164) for charging the second capacitor (122), the second means having an input coupled to receive the output voltage of the first means, the second means further having an output coupled to the second capacitor.
19. The reset circuit of claim 18 wherein the second means includes means for delaying the onset of the charging of the second capacitor.
20. [Cancelled]
21. The reset circuit of claim 18 wherein each of the transistors has a zero threshold voltage.
22. The reset circuit of claim 20 wherein the pair of transistors (150, 152) is coupled at a second node (B);
the second means includes a P-channel transistor and an N-channel transistor coupled in series between the first and second terminals, a gate of each being coupled to the second node; and a source of the P-channel transistor and a drain of the N-channel transistor are coupled to charge the second capacitor.
the second means includes a P-channel transistor and an N-channel transistor coupled in series between the first and second terminals, a gate of each being coupled to the second node; and a source of the P-channel transistor and a drain of the N-channel transistor are coupled to charge the second capacitor.
23. The reset circuit of claim 18 wherein the first terminal is a power supply rail and the second terminal is a ground rail.
24. A power-on reset circuit comprising:
a power connection (110);
a ground connection;
an output node A;
a first capacitor (120) coupled between the power node and the output node;
first and second transistors (150, 152) coupled in series between the power connection and the ground connection, the first and second transistors coupled together at a node B;
third and fourth transistors (140, 142) coupled in series between the power connection and the ground connection, the third and fourth transistors coupled together at a node C, the third and fourth transistors each having a gate coupled to node B;
a second capacitor (122) coupled between node C
and the ground connection;
a first inverter (130) having an input coupled to node C and an output coupled to node A; and a feedback path (160) coupling the output node to gate terminals of the first and second transistors.
a power connection (110);
a ground connection;
an output node A;
a first capacitor (120) coupled between the power node and the output node;
first and second transistors (150, 152) coupled in series between the power connection and the ground connection, the first and second transistors coupled together at a node B;
third and fourth transistors (140, 142) coupled in series between the power connection and the ground connection, the third and fourth transistors coupled together at a node C, the third and fourth transistors each having a gate coupled to node B;
a second capacitor (122) coupled between node C
and the ground connection;
a first inverter (130) having an input coupled to node C and an output coupled to node A; and a feedback path (160) coupling the output node to gate terminals of the first and second transistors.
25. The reset circuit of claim 24 wherein the first and second transistors (150, 152) are zero threshold voltage N-channel devices.
26. The reset circuit of claim 24 wherein the third transistor (140) is a P-channel device and the fourth transistor (142) is a zero threshold voltage N-channel device.
27. The reset circuit of claim 24 wherein the first and second transistors are zero threshold voltage N-channel devices, the third transistor is a P-channel device, and the fourth transistor is a zero threshold voltage N-channel device.
28. The reset circuit of claim 27 further including a second inverter (106) having an input coupled to the output node, whereby the output node serves as a reset signal and an output of the second inverter serves as a complement of the reset signal.
29. The reset circuit of claim 28 further including a third inverter (102) having an input coupled to the output of the second inverter (106), and a fourth inverter (104) coupled to an output of the third inverter, whereby the output of the third inverter serves as the reset signal and an output of the fourth inverter serves as a complement of the reset signal.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/977,779 | 1997-11-25 | ||
| US08/977,779 US5936444A (en) | 1997-11-25 | 1997-11-25 | Zero power power-on reset circuit |
| PCT/US1998/024630 WO1999027652A1 (en) | 1997-11-25 | 1998-11-20 | Zero power power-on-reset circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2303234A1 true CA2303234A1 (en) | 1999-06-03 |
Family
ID=25525507
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002303234A Abandoned CA2303234A1 (en) | 1997-11-25 | 1998-11-20 | Zero power power-on-reset circuit |
Country Status (12)
| Country | Link |
|---|---|
| US (1) | US5936444A (en) |
| EP (1) | EP1034619B1 (en) |
| JP (1) | JP2001527303A (en) |
| KR (1) | KR20010024289A (en) |
| CN (1) | CN1173473C (en) |
| CA (1) | CA2303234A1 (en) |
| DE (1) | DE69840271D1 (en) |
| HK (1) | HK1033216A1 (en) |
| MY (1) | MY114494A (en) |
| NO (1) | NO20002194L (en) |
| TW (1) | TW420906B (en) |
| WO (1) | WO1999027652A1 (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6288587B1 (en) * | 1999-04-07 | 2001-09-11 | National Science Council Of Republic Of China | CMOS pulse shrinking delay element with deep subnanosecond resolution |
| US6362669B1 (en) * | 2000-04-10 | 2002-03-26 | Xilinx, Inc. | Structure and method for initializing IC devices during unstable power-up |
| US6288584B1 (en) | 2000-10-05 | 2001-09-11 | Pericom Semiconductor Corp. | Zero standby-current power-on reset circuit with Schmidt trigger sensing |
| DE10146831B4 (en) | 2001-09-24 | 2006-06-22 | Atmel Germany Gmbh | Method for generating a time-limited signal |
| US6747492B2 (en) | 2002-06-18 | 2004-06-08 | Koninklijke Philips Electronics N.V. | Power-on reset circuit with current shut-off and semiconductor device including the same |
| US6744291B2 (en) | 2002-08-30 | 2004-06-01 | Atmel Corporation | Power-on reset circuit |
| US7348814B2 (en) | 2004-08-24 | 2008-03-25 | Macronix International Co., Ltd. | Power-on reset circuit |
| US7934042B2 (en) * | 2004-10-14 | 2011-04-26 | International Business Machines Corporation | Voltage indicator signal generation system and method |
| US7131092B2 (en) * | 2004-12-21 | 2006-10-31 | Via Technologies, Inc. | Clock gating circuit |
| US20070001721A1 (en) * | 2005-07-01 | 2007-01-04 | Chi-Yang Chen | Power-on reset circuit |
| KR101003151B1 (en) * | 2009-05-14 | 2010-12-21 | 주식회사 하이닉스반도체 | Circuit for Generating Power-up Signal of a Semiconductor Memory Apparatus |
| US9092045B2 (en) | 2013-04-18 | 2015-07-28 | Freescale Semiconductor, Inc. | Startup circuits with native transistors |
| US10254317B1 (en) | 2018-04-17 | 2019-04-09 | Nxp Usa, Inc. | Low-current circuits for supply voltage level detection |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4409501A (en) * | 1981-07-20 | 1983-10-11 | Motorola Inc. | Power-on reset circuit |
| US4634904A (en) * | 1985-04-03 | 1987-01-06 | Lsi Logic Corporation | CMOS power-on reset circuit |
| US4746822A (en) * | 1986-03-20 | 1988-05-24 | Xilinx, Inc. | CMOS power-on reset circuit |
| FR2616602B1 (en) * | 1987-06-12 | 1989-10-13 | Thomson Semiconducteurs | POWER ON CIRCUIT FOR MOS TECHNOLOGY INTEGRATED CIRCUIT |
| JP3409938B2 (en) * | 1995-03-02 | 2003-05-26 | 株式会社東芝 | Power-on reset circuit |
| DE69624786D1 (en) * | 1996-02-02 | 2002-12-19 | St Microelectronics Srl | Power-on reset circuit with zero consumption |
| US5703510A (en) * | 1996-02-28 | 1997-12-30 | Mitsubishi Denki Kabushiki Kaisha | Power on reset circuit for generating reset signal at power on |
-
1997
- 1997-11-25 US US08/977,779 patent/US5936444A/en not_active Expired - Lifetime
-
1998
- 1998-11-20 CN CNB988115239A patent/CN1173473C/en not_active Expired - Fee Related
- 1998-11-20 CA CA002303234A patent/CA2303234A1/en not_active Abandoned
- 1998-11-20 JP JP2000522680A patent/JP2001527303A/en not_active Withdrawn
- 1998-11-20 WO PCT/US1998/024630 patent/WO1999027652A1/en not_active Application Discontinuation
- 1998-11-20 EP EP98958071A patent/EP1034619B1/en not_active Expired - Lifetime
- 1998-11-20 DE DE69840271T patent/DE69840271D1/en not_active Expired - Fee Related
- 1998-11-20 KR KR1020007003182A patent/KR20010024289A/en not_active Application Discontinuation
- 1998-11-24 MY MYPI98005319A patent/MY114494A/en unknown
- 1998-11-25 TW TW087119555A patent/TW420906B/en not_active IP Right Cessation
-
2000
- 2000-04-27 NO NO20002194A patent/NO20002194L/en not_active Application Discontinuation
-
2001
- 2001-06-07 HK HK01103929A patent/HK1033216A1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| CN1173473C (en) | 2004-10-27 |
| EP1034619B1 (en) | 2008-11-26 |
| WO1999027652A1 (en) | 1999-06-03 |
| DE69840271D1 (en) | 2009-01-08 |
| HK1033216A1 (en) | 2001-08-17 |
| NO20002194D0 (en) | 2000-04-27 |
| EP1034619A4 (en) | 2003-09-10 |
| NO20002194L (en) | 2000-07-24 |
| JP2001527303A (en) | 2001-12-25 |
| MY114494A (en) | 2002-10-31 |
| US5936444A (en) | 1999-08-10 |
| EP1034619A1 (en) | 2000-09-13 |
| KR20010024289A (en) | 2001-03-26 |
| CN1290426A (en) | 2001-04-04 |
| TW420906B (en) | 2001-02-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |