1PS8703 09/23/03
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 manual-
reset 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 (µP)
supervisory circuits are targeted to improve reliability and
accuracy of power-supply circuitry in µP 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-µp, power-down and
brownout conditions for µP 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
Low Cost µP Supervisor Circuts
PI4S705, PI4S706x,PI4S707,
PI4S708x, PI4S813L
Product Pin Conguration
1
2
3
4
8
7
6
5
MR
V
CC
GND
PFI
WDO
RESET
WDI
PFO
1
2
3
4
8
7
6
5
MR
VCC
GND
PFI
WDO
RESET
WDI
PFO
1
2
3
4
8
7
6
5
MR
VCC
GND
PFI
RESET
RESET
NC
PFO
PI74S705
PI74S706
PI74S706T
PI74S706S
PI74S706R
PI74S813L
PI4S706H
PI4S706TH
PI4S706SH
PI4S706P
PI74S707
PI74S708
PI74S708T
PI74S708S
PI74S708R
Top View
2PS8703 09/23/03
PI4S705, PI4S706x, PI4S707, PI4S708x, PI4S813L
µP Supervisor Circuts
Pin Name Type Description
MR Input
Manual-Reset: triggers a reset pulse when pulled below 0.8V, active low. It has an internal 250μA
pull-up current and can be driven from a TTL or CMOS logic line as well as shorted to ground with a
switch.
VCC Power Power Supply
GND Ground Ground Reference for all signals
PFI Input Power-Fail Voltage Monitor Input: When PFI is less than 1.25V, PFO goes low. Connect PFI to GND
or Vcc when not used.
PFO Output Power-Fail Output: it gets low and sinks current when PFI is less than 1.25V; otherwise PFO stays
high.
WDI Input
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.
NC No Connect
RESET 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.
WDO Output
Watchdog Output: pulls low when the internal watchdog timer nishes 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 mini-
mum pulse width. As soon as VCC rises above the reset threshold, WDO goes high with no delay.
RESET Output The inverse of RESET: active high. Whenever RESET is high, RESET is low.
Pin Descriptiom
3PS8703 09/23/03
PI4S705, PI4S706x, PI4S707, PI4S708x, PI4S813L
µP Supervisor Circuts
Block Diagram for PI4S707, PI4S708x
Block Diagram for PI7S705, PI4S706x, PI4S706xH, PI4S813L
Vcc
250uA
V
RST
1.25V
Watchdog
Transition Detector
Watchdog Timer
WDI WDO
Timebase for Reset
& Watchdog
Reset Generator
MR
Vcc
PFI
RESET
(RESET)
PFO
*
Reset Generator
MR
Vcc
PFI
PFO
RESE
T
1.25V
V
RST
Vcc
250uA RESE
T
*
*VRST = RESET Threshold Voltage
*VRST = RESET Threshold Voltage
4PS8703 09/23/03
PI4S705, PI4S706x, PI4S707, PI4S708x, PI4S813L
µP 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.
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 µPs,
such as Intel’s 80C51, require an active-high reset pulse.
Watchdog Timer
The watchdog circuit monitors the µP’s activity. If the µP 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 µP. 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 oating WDI disables the internal timer, WDO goes low
only when VCC falls below the reset threshold, thus functioning
as a low-line output.
Manual Reset
The manual-reset input (MR) allows reset to be triggered by a push-
button 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
DC Linear
Regulator
Vcc
Supervisory
PFI
Circuit
WDI
µP
Vcc
RESET
I/O Line
NMI
Interrupt
IN
OUT
RESET
WDO
PFOMR
µP
Unregulated DC
5PS8703 09/23/03
PI4S705, PI4S706x, PI4S707, PI4S708x, PI4S813L
µP Supervisor Circuts
Function Reference Table
Part No. Reset
Threshold
Reset Active Low
or High
Nom. Reset
Time (ms),
tRS
Nom. Watchdog
Time (sec), tWD
Power Fail
Comp.
Manual Reset
Input
PI4S705 4.63V LOW 200 1.6 1.25V detector Yes
PI4S813L 4.63V HIGH 200 1.6 1.25V detector Yes
PI4S707 4.63V LOW, HIGH 200 unavailable 1.25V detector Yes
PI4S706 4.38V LOW 200 1.6 1.25V detector Yes
PI4S706H 4.38V HIGH 200 1.6 1.25V detector Yes
PI4S708 4.38V LOW, HIGH 200 unavailable 1.25V detector Yes
PI4S706T 3.08V LOW 200 1.6 1.25V detector Yes
PI4S706TH 3.08V HIGH 200 1.6 1.25V detector Yes
PI4S708T 3.08V LOW, HIGH 200 unavailable 1.25V detector Yes
PI4S706S 2.93V LOW 200 1.6 1.25V detector Yes
PI4S706SH 2.93V HIGH 200 1.6 1.25V detector Yes
PI4S708S 2.93V LOW, HIGH 200 unavailable 1.25V detector Yes
PI4S706R 2.63V LOW 200 1.6 1.25V detector Yes
PI4S706P 2.63V HIGH 200 1.6 1.25V detector Yes
PI4S708R 2.63V LOW, HIGH 200 unavailable 1.25V detector Yes
Symbol Description Test Conditions Min Typ Max Unit
VCC Supply Voltage for PI4S70xxx, 813L 1.2 5.5
V
VIH1 MR Input High Voltage VCC > 4.0V 2 2.4
VCC ≤ 4.0V 0.7 x VCC
VIH2 WDI Input High Voltage 0.7 x VCC
VIL1 MR Input Low Voltage VCC > 4.0V 0.8
VCC ≤ 4.0V 0.2 x VCC
VIL2 WDI Input Low Voltage 0.3 x VCC
TAOperating Temperature 0 70 ºC
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 = 0ºC to 70°C; unless otherwise noted.)
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
Absolute Maximum Ratings
Note:
Stresses greater than those listed under MAXIMUM
RATINGS may cause permanent damage to the de-
vice. This is a stress rating only and functional opera-
tion of the device at these or any other conditions
above those indicated in the operational sections
of this specication is not implied. Exposure to
absolute maximum rating conditions for extended
periods may affect reliability.
6PS8703 09/23/03
PI4S705, PI4S706x, PI4S707, PI4S708x, PI4S813L
µP Supervisor Circuts
Symbol Description Test Conditions Min Typ Max Unit
ICC Operational Power Supply
Current
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)
30 200 µA
VRST Reset Threshold Voltage *
PI4S705, 707, 813L 4.50 4.63 4.75
V
PI4S706, 706H, 708 4.25 4.38 4.50
PI4S706T, 706TH, 708T 3.00 3.08 3.15
PI4S706S, 706SH, 708S 2.85 2.93 3.00
PI4S706P, 706R, 708R 2.55 2.63 2.70
VRTH Reset Threshold Hysteresis * 70 mV
VOH Output HIGH Voltage
VCC > 4.5V Isource = 800μA VCC-1.5
V
VCC > 2.7V Isource = 500μA 0.8 x VCC
VCC ≥ 1.2V Isource = 4μA 0.8 x VCC
VOL Output LOW Voltage
VCC > 4.5V Isink = 3.2mA 0.4
VCC > 2.7V Isink = 1.2mA 0.3
VCC ≥ 1.2V Isink = 50μA 0.3
VPFT PFI Input Threshold VPFI varies from1.0V to 1.5V 1.20 1.25 1.30
IPFI PFI Input Current PFI connected to VCC 2
µA
PFI connected to GND -2
IWDI Average WDI Input Current** WDI connected to VCC 30 100
WDI connected to GND -100 -30
IMR MR Input Current MR = 0, VCC = 5V -600 -250 -100
DC Electrical Characteristics (Continued)
* Valid for both RESET and RESET.
** WDI is internally serviced within the watchdog period if WDI is left unconnected.
7PS8703 09/23/03
PI4S705, PI4S706x, PI4S707, PI4S708x, PI4S813L
µP Supervisor Circuts
Symbol Description Test Conditions Min Typ Max Units
tRS Reset Pulse Width MR from low to High 140 200 280 ms
tWD Watchdog Timeout Period WDI and MR tied to VCC 1 1.6 2.25 s
tMR MR Pulse Width 150
nstMD MR to RESET Output Delay VCC = 5.0V 250
tWP WDI Pulse Width 50
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 = 0ºC to 70°C; unless otherwise noted.)
Watchdog Timing Diagram
RESET, MR, and WDO Timing Diagram with WDI 3-stated. (RESET output is the inverse of RESET shown).
t
WP
t
WD
t
WD
t
WD
t
RS
Externally
Triggered by MR
WDI
WDO
RESET
RESET
5
V
0
V
5
V
0
V
5
V
0
V
5
V
0
V
V
V
V
V
V
V
V
V
8PS8703 09/23/03
PI4S705, PI4S706x, PI4S707, PI4S708x, PI4S813L
µP Supervisor Circuts
Packaging Mechanical: 8-pin 150-mil wide plastic SOIC (W)
.0040
.0098
SEATING PLANE
.013
.020
.050
BSC
.016
.0075
.0098
1
8
.0099
.0196
0-8˚
.050
.149
.157
X.XX
X.XX
DENOTES DIMENSIONS
IN MILLIMETERS
3.78
3.99
.189
.196
4.80
5.00
1.27
.016
.026 1.35
1.75
.2284
.2440
5.80
6.20
0.406
0.660
0.330
0.508
0.10
0.25
0.40
1.27
0.19
0.25
0.25
0.50 x 45˚
.053
.068
REF
Ordering Information
Notes:
1. Thermal characteristics can be found on the company web site at http://www.pericom.com/packaging/mechanicals.php
Ordering Code Packaging Code Package Type Reset Threshold
PI4S705W W 8-pin, 150 mil wide plastic SOIC 4.63V
PI4S813LW W 8-pin, 150 mil wide plastic SOIC 4.63V
PI4S707W W 8-pin, 150 mil wide plastic SOIC 4.63V
PI4S706W W 8-pin, 150 mil wide plastic SOIC 4.38V
PI4S706HW W 8-pin, 150 mil wide plastic SOIC 4.38V
PI4S708W W 8-pin, 150 mil wide plastic SOIC 4.38V
PI4S706TW W 8-pin, 150 mil wide plastic SOIC 3.08V
PI4S706THW W 8-pin, 150 mil wide plastic SOIC 3.08V
PI4S708TW W 8-pin, 150 mil wide plastic SOIC 3.08V
PI4S706SW W 8-pin, 150 mil wide plastic SOIC 2.93V
PI4S706SHW W 8-pin, 150 mil wide plastic SOIC 2.93V
PI4S708SW W 8-pin, 150 mil wide plastic SOIC 2.93V
PI4S706RW W 8-pin, 150 mil wide plastic SOIC 2.63V
PI4S706PW W 8-pin, 150 mil wide plastic SOIC 2.63V
PI4S708RW W 8-pin, 150 mil wide plastic SOIC 2.63V
Pericom Semiconductor Corporation
2380 Bering Drive • San Jose, CA 95131 • 1-800-435-2336 • Fax (408) 435-1100 • http://www.pericom.com