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PI4S705, PI4S706x,PI4S707, PI4S708x, PI4S813L
Low Cost P Supervisor Circuts
Product Features
* Precision supply-voltage monitor - 4.63V (PI4S705, PI4S813L, PI4S707) - 4.38V (PI4S706, PI4S706H, PI4S708) - 3.08V (PI4S706T, PI4S706TH, PI4S708T) - 2.93V (PI4S706S, PI4S706SH, PI4S708S) - 2.63V (PI4S706R, PI4S706P, PI4S708R) * 200ms reset pulse width * Debounced TTL/CMOS-compatible manualreset input * Independent watchdog timer with 1.6sec time-out (PI4S705, 706x, 706xH, and 813L ONLY ) * Reset output signal: - Active-low only (PI4S705, 706, 706T, 706S, 706R) - Active-high only (PI4S813L, 706H, 706TH, 706SH, 706P) - Active-high and active-low (PI4S707, 708, 708T, 708S, 708R) * Voltage monitor for power-fail or low battery warning * Guaranteed RESET/RESET valid at VCC = 1.2V
Description
The PI4S70xxx/PI4S813L family microprocessor (P) supervisory circuits are targeted to improve reliability and accuracy of power-supply circuitry in P systems. These devices reduce the complexity and number of components required to monitor power-supply and battery functions. The main functions are: 1. Asserting reset output during power-p, power-down and brownout conditions for P systems. 2. Detecting power failure or low-battery conditions with a 1.25V threshold detector. 3. Generating an independent watchdog output that goes low if the watchdog input has not been toggled within 1.6 seconds. 4. Asserting reset output with an active-low manual-reset input
Applications
* Computers * Controllers * Intelligent Instruments * Automotive Systems * Printers * Critical Microprocessor Power Monitoring
Product Pin Configuration
MR
1 2 3 4
8 7 6 5
WDO RESET WDI PFO
MR V CC GND PFI
1 2 3 4
8 7 6 5
WDO RESET WDI PFO
MR V CC GND PFI
1 2 3 4
8 7 6 5 PI74S707 PI74S708 PI74S708T PI74S708S PI74S708R
RESET RESET NC PFO
VCC
GND PFI
PI74S705 PI74S706 PI74S706T PI74S706S PI74S706R
PI74S813L PI4S706H PI4S706TH PI4S706SH PI4S706P Top View
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PS8703
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PI4S705, PI4S706x, PI4S707, PI4S708x, PI4S813L
P Supervisor Circuts
Pin Descriptiom
Pin Name MR VCC GND PFI PFO Type Input Power Ground Input Output Description Manual-Reset: triggers a reset pulse when pulled below 0.8V, active low. It has an internal 250A pull-up current and can be driven from a TTL or CMOS logic line as well as shorted to ground with a switch. Power Supply Ground Reference for all signals Power-Fail Voltage Monitor Input: When PFI is less than 1.25V, PFO goes low. Connect PFI to GND or Vcc when not used. Power-Fail Output: it gets low and sinks current when PFI is less than 1.25V; otherwise PFO stays high. Watchdog Input: If WDI remains high or low for 1.6sec, the internal watchdog timer runs out and WDO goes low. Floating WDI or connecting WDI to a high-impedance three-state buffer disables the watchdog feature. The internal watchdog timer clears whenever reset is asserted, WDI is three-stated, or WDI sees a rising or falling edge. No Connect Output Reset Output pulses: low for 200ms when triggered, and stays low whenever Vcc is below the reset threshold. It remains low for 200ms after VCC rises above the reset threshold or MR goes from low to high. A watchdog timeout will not trigger RESET unless WDO is connected to MR. Watchdog Output: pulls low when the internal watchdog timer finishes its 1.6sec count and does not go high again until the watchdog is cleared. WDO also goes low during low-line conditions. Whenever Vcc is below the reset threshold, WDO stays low; however, unlike RESET, WDO does not have minimum pulse width. As soon as VCC rises above the reset threshold, WDO goes high with no delay. The inverse of RESET: active high. Whenever RESET is high, RESET is low.
WDI NC RESET
Input
WDO RESET
Output Output
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PS8703
09/23/03
PI4S705, PI4S706x, PI4S707, PI4S708x, PI4S813L
P Supervisor Circuts
Block Diagram for PI7S705, PI4S706x, PI4S706xH, PI4S813L
WDI
Watchdog Transition Detector
V cc 250uA
Watchdog Timer
WDO
Timebase for Reset & Watchdog
Reset Generator
MR Vcc
V RST
RESET (RESET)
*
PFI
1.25V
PFO
*VRST = RESET Threshold Voltage
Block Diagram for PI4S707, PI4S708x
Vcc 250uA MR Vcc
Reset Generator
RESET
RESET
* V RST
PFI PFO 1.25V
*VRST = RESET Threshold Voltage
3
PS8703
09/23/03
PI4S705, PI4S706x, PI4S707, PI4S708x, PI4S813L
P Supervisor Circuts
Functional Description
The PI4S70xxx/813L family can assert reset output during power-up, power-down and brownout conditions for uP system, detect power failure or low-battery conditions with a 1.25V threshold detector and have watchdog functions. Refer to Function Reference Table for their individual features. For the typical application see Figure 4.
Watchdog Timer
The watchdog circuit monitors the P's activity. If the P does not toggle the watchdog input (WDI) within 1.6sec and WDI is not in high impedance, WDO goes low. As long as RESET is asserted or the WDI input is in high impedance, the watchdog timer will stay cleared and will not count. As soon as reset is released and WDI is driven high or low, the timer will start counting. Pulses as short as 50ns can be detected. Typically, WDO will be connected to the non-maskable interrupt input (NMI) of a P. When VCC drops below the reset threshold, WDO will go low whether or not the watchdog timer has timed out yet. Normally this would trigger an NMI interrupt, but RESET goes low simultaneously, and thus overrides the NMI interrupt. If WDI is left unconnected, WDO can be used as a low-line output. Since floating WDI disables the internal timer, WDO goes low only when VCC falls below the reset threshold, thus functioning as a low-line output.
Reset Output
The supervisory circuits can assert reset for a microprocessor during power-up, power-down and brownout to prevent code execution errors. On power-up, once VCC reaches about 1.2V, RESET is a guaranteed logic low of 0.4V or less. As VCC rises, RESET stays low. When VCC rises above the reset threshold, an internal timer releases RESET after about 200ms. RESET pulses low whenever VCC drops below the reset threshold (brownout condition). If brownout occurs in the middle of a previously initiated reset pulse, the pulse continues for at least another 140ms. On power-down, once VCC falls below the reset threshold, RESET stays low and is guaranteed to be 0.4V or less until Vcc drops below 1.2V. The PI4S706xH, PI4S707, PI4S708x and PI4S813L active-high RESET output is simply the complement of the RESET output, and is guaranteed to be valid with VCC down to 1.2V. Some Ps, such as Intel's 80C51, require an active-high reset pulse.
Manual Reset
The manual-reset input (MR) allows reset to be triggered by a pushbutton switch. The switch is effectively debounced by the 140ms minimum reset pulse width. MR is TTL/CMOS logic compatible, so it can be driven by any external logic line.
Power-Fail Comparator
The power-fail comparator will send out a low signal once detects a voltage lowered than 1.25V. It can be used for various purposes because its output and non-inverting input are not internally connected. The inverting input is internally connected to a 1.25V reference.
Typical Application Circuit
Unregulated DC IN DC Linear Regulator OUT
P Vcc Vcc PFI MR RESET I/O Line NMI Interrupt
RESET P Supervisory Circuit WDI WDO PFO
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PS8703
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PI4S705, PI4S706x, PI4S707, PI4S708x, PI4S813L
P Supervisor Circuts
Function Reference Table
Part No. PI4S705 PI4S813L PI4S707 PI4S706 PI4S706H PI4S708 PI4S706T PI4S706TH PI4S708T PI4S706S PI4S706SH PI4S708S PI4S706R PI4S706P PI4S708R Reset Threshold 4.63V 4.63V 4.63V 4.38V 4.38V 4.38V 3.08V 3.08V 3.08V 2.93V 2.93V 2.93V 2.63V 2.63V 2.63V Reset Active Low or High LOW HIGH LOW, HIGH LOW HIGH LOW, HIGH LOW HIGH LOW, HIGH LOW HIGH LOW, HIGH LOW HIGH LOW, HIGH Nom. Reset Time (ms), tRS 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 Nom. Watchdog Time (sec), tWD 1.6 1.6 unavailable 1.6 1.6 unavailable 1.6 1.6 unavailable 1.6 1.6 unavailable 1.6 1.6 unavailable Power Fail Comp. 1.25V detector 1.25V detector 1.25V detector 1.25V detector 1.25V detector 1.25V detector 1.25V detector 1.25V detector 1.25V detector 1.25V detector 1.25V detector 1.25V detector 1.25V detector 1.25V detector 1.25V detector Manual Reset Input Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Absolute Maximum Ratings
Storage Temperature .....................................................-65oC to +150oC Ambient Temperature with Power Applied .......................0oC to +70oC Supply Voltage to Ground Potential (VCC to GND) ....... -0.3V to +7.0V DC Input Voltage (All inputs except VCC and GND) ........ -0.3V to VCC+0.3V DC Output Current (All outputs) ................................................... 20mA Power Dissipation (W package) ................................................. 500mW
Note: Stresses greater than those listed under MAXIMUM RATINGS may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability.
DC Electrical Characteristics
(VCC =4.75V to 5.5V for PI4S705, PI4S813L, PI4S707 ; VCC = 4.5V to 5.5V for PI4S706, PI4S706H, PI4S708; VCC = 3.15V to 5.5V for PI4S706T, PI4S706TH, PI4S708T; VCC = 3.0V to 5.5V for PI4S706S, PI4S706SH, PI4S708S; VCC = 2.7V to 5.5V for PI4S706R, PI4S706P, PI4S708R; TA = 0C to 70C; unless otherwise noted.) Symbol VCC VIH1 VIH2 VIL1 VIL2 TA Description Supply Voltage for PI4S70xxx, 813L MR Input High Voltage WDI Input High Voltage MR Input Low Voltage WDI Input Low Voltage Operating Temperature 0 VCC > 4.0V VCC 4.0V VCC > 4.0V VCC 4.0V Test Conditions Min 1.2 2 0.7 x VCC 0.7 x VCC 0.8 0.2 x VCC 0.3 x VCC 70 C 2.4 V Typ Max 5.5 Unit
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PS8703
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PI4S705, PI4S706x, PI4S707, PI4S708x, PI4S813L
P Supervisor Circuts
DC Electrical Characteristics (Continued)
Symbol Description Operational Power Supply Current Test Conditions PI4S705, 706, 706H, 707, 708, 813L, VCC = 5V; PI4S706S, 706SH, 706T, 706TH, 708S, 708T, VCC = 3.3V; PI4S706P, 706R, 708R, VCC = 3.0V; Left WDI un-connected (No output load) PI4S705, 707, 813L PI4S706, 706H, 708 VRST Reset Threshold Voltage * PI4S706T, 706TH, 708T PI4S706S, 706SH, 708S PI4S706P, 706R, 708R VRTH VOH Reset Threshold Hysteresis * VCC > 4.5V Isource = 800A Output HIGH Voltage VCC > 2.7V Isource = 500A VCC 1.2V Isource = 4A VCC > 4.5V Isink = 3.2mA VOL VPFT IPFI IWDI IMR Output LOW Voltage PFI Input Threshold PFI Input Current Average WDI Input Current** MR Input Current VCC > 2.7V Isink = 1.2mA VCC 1.2V Isink = 50A VPFI varies from1.0V to 1.5V PFI connected to VCC PFI connected to GND WDI connected to VCC WDI connected to GND MR = 0, VCC = 5V -100 -600 -2 30 -30 -250 -100 100 A 1.20 1.25 VCC-1.5 0.8 x VCC 0.8 x VCC 0.4 0.3 0.3 1.30 2 V 4.50 4.25 3.00 2.85 2.55 Min Typ Max Unit
ICC
30
200
A
4.63 4.38 3.08 2.93 2.63 70
4.75 4.50 3.15 3.00 2.70 mV V
* Valid for both RESET and RESET. ** WDI is internally serviced within the watchdog period if WDI is left unconnected.
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PS8703
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PI4S705, PI4S706x, PI4S707, PI4S708x, PI4S813L
P Supervisor Circuts
AC Electrical Characteristics
(VCC =4.75V to 5.5V for PI4S705, PI4S813L, PI4S707 ; VCC = 4.5V to 5.5V for PI4S706, PI4S706H, PI4S708; VCC = 3.15V to 5.5V for PI4S706T, PI4S706TH, PI4S708T; VCC = 3.0V to 5.5V for PI4S706S, PI4S706SH, PI4S708S; VCC = 2.7V to 5.5V for PI4S706R, PI4S706P, PI4S708R; TA = 0C to 70C; unless otherwise noted.) Symbol tRS tWD tMR tMD tWP Description Reset Pulse Width Watchdog Timeout Period MR Pulse Width MR to RESET Output Delay WDI Pulse Width VCC = 5.0V 50 Test Conditions MR from low to High WDI and MR tied to VCC Min 140 1 150 250 ns Typ 200 1.6 Max 280 2.25 Units ms s
Watchdog Timing Diagram
tWP tWD tWD tWD
5V
WDI WDO
0V 5V 0V
RESET
Externally Triggered by MR
5V 0V
tRS
5V 0V
RESET
RESET, MR, and WDO Timing Diagram with WDI 3-stated. (RESET output is the inverse of RESET shown).
V CC V RT V RT tRS tRS
5V 0V 5V 0V
RESET MR tMD tMR WDO
5V 0V
5V 0V
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PS8703
09/23/03
PI4S705, PI4S706x, PI4S707, PI4S708x, PI4S813L
P Supervisor Circuts
Packaging Mechanical: 8-pin 150-mil wide plastic SOIC (W)
8
.149 .157
3.78 3.99
.0099 .0196
0.25 x 45 0.50
1
0-8
.0075 .0098
0.19 0.25
.189 .196
4.80 5.00
0.40 .016 1.27 .050
.016 .026 0.406 0.660
.053 .068
1.35 1.75
SEATING PLANE
.2284 .2440 5.80 6.20
REF
.050 BSC 1.27
.013 0.330 .020 0.508
.0040 0.10 .0098 0.25
X.XX DENOTES DIMENSIONS X.XX IN MILLIMETERS
Ordering Information
Ordering Code PI4S705W PI4S813LW PI4S707W PI4S706W PI4S706HW PI4S708W PI4S706TW PI4S706THW PI4S708TW PI4S706SW PI4S706SHW PI4S708SW PI4S706RW PI4S706PW PI4S708RW Packaging Code W W W W W W W W W W W W W W W Package Type 8-pin, 150 mil wide plastic SOIC 8-pin, 150 mil wide plastic SOIC 8-pin, 150 mil wide plastic SOIC 8-pin, 150 mil wide plastic SOIC 8-pin, 150 mil wide plastic SOIC 8-pin, 150 mil wide plastic SOIC 8-pin, 150 mil wide plastic SOIC 8-pin, 150 mil wide plastic SOIC 8-pin, 150 mil wide plastic SOIC 8-pin, 150 mil wide plastic SOIC 8-pin, 150 mil wide plastic SOIC 8-pin, 150 mil wide plastic SOIC 8-pin, 150 mil wide plastic SOIC 8-pin, 150 mil wide plastic SOIC 8-pin, 150 mil wide plastic SOIC Reset Threshold 4.63V 4.63V 4.63V 4.38V 4.38V 4.38V 3.08V 3.08V 3.08V 2.93V 2.93V 2.93V 2.63V 2.63V 2.63V
Notes: 1. Thermal characteristics can be found on the company web site at http://www.pericom.com/packaging/mechanicals.php
Pericom Semiconductor Corporation 2380 Bering Drive * San Jose, CA 95131 * 1-800-435-2336 * Fax (408) 435-1100 * http://www.pericom.com
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PS8703 09/23/03

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