1P-0.2 02/24/05
ADVANCE INFORMATION, COMPANY CONFIDENTIAL
Features
• Precision supply-voltage monitor
- 4.63V (PI4S8xxL)
- 4.38V (PI4S8xxM)
- 3.08V (PI4S8xxT)
- 2.93V (PI4S8xxS)
- 2.63V (PI4S8xxR)
- 2.32V (PI4S8xxZ)
- 2.20V (PI4S8xxY)
• 200ms reset pulse width
• Reset Output Signal for Watchog and Power Abnormal,
Manual Reset
• Reset Push-Pull output (PI4S809)
• Voltage monitor for power-fail or low battery warning
• Guaranteed RESET/RESET valid at VCC = 1.2V
• Packaging: 3-pin SOT-23
Description
The PI4Sxxx 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:
• Asserting reset output during power-µp, power-down and
brownout conditions for µP systems.
• Detecting power failure or low-battery conditions with a 1.25V
threshold detector.
• Watchdog functions.
• Manual reset.
Applications
• Power-supply circuitry in µP systems.
µP Supervisor Circuits
PI4S809/803
Block Diagram
Reset Generator
VCC
GND
200ms
RESET
VREF
Pin Conguration
1
3
2
GND
V
CC
RESET
PI74S803
PI74S809
2P-0.2 02/24/05
PI4S809/803
µP Supervisor Circuits
ADVANCE INFORMATION, COMPANY CONFIDENTIAL
Pin Name Type Description
VCC Power Power Supply: Reset is asserted when VCC drops below the Reset Threshold Voltage (VRST). Reset
remains asserted until VCC rises abouv VRES and keep asserted for the duration for the Reset Timeout
Period (tRS) once VCC rises above (VRST).
GND Ground Ground Reference for all signals
RESET O Active-Low Reset Output (Push-Pull or Open-Drain). It goes low when VCC is below the reset
threshold. It remains low for about 200ms after one of the following occurs: VCC rises above the reset
threshold (VRST), the watchdog triggers a reset, or MR goes from low to high.
Pin Description (Table 2.)
Functional Description
Reset Output
A microprocessor (µP) reset input starts the µP in a known state.
Whenever the µP is in an unknown state, it should be held in
reset. The supervisory circuits assert reset during power-up and
prevent code execution errors during power-down or brownout
conditions.
On power-up, once VCC reaches about 1.0V, 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, i.e. brownout condition. If brownout
occurs in the middle of a previously initiated reset pulse, the pulse
continues for at least another 200ms. 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 1.0V. Figure 4 shows the
timing relationship.
The active-high RESET output is simply the inverse of the RESET
output, and is guaranteed to be valid with VCC down to 1.0V.
Storage Temperature ......................................................... -65oC to +150oC
Ambient Temperature with Power Applied ........................ -40oC to +85oC
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 (Depends on package) ..................................... 320mW
Absolute Maximum Ratings
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 specication
is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect reliability.
3P-0.2 02/24/05
PI4S809/803
µP Supervisor Circuits
ADVANCE INFORMATION, COMPANY CONFIDENTIAL
DC Electrical Characteristics (Table 3)
Symbol Description Test Conditions Min Typ Max Unit
VCC
Supply Voltage for xxxL, xxxM 4.5 5.0
5.5
V
Supply Voltage for xxxT, xxxS 3.0 3.3
Supply Voltage for xxxR 2.7 3.0
Supply Voltage for xxxZ, xxxY 2.4 2.5
VIH Input High Voltage 0.7VCC
VIL Input Low Voltage 0.3VCC
TAOperating Temperature -40 85 ºC
DC Electrical Characteristics (Table 4)
Symbol Description Test Conditions Min Typ Max Unit
VCC Operating Voltage Range 1.0 5.5 V
ICC Supply Current VCC = 5V No Load 6 18 uA
VIH Input High Voltage 0.7xVCC V
VIL Input Low Voltage 0.3xVcc V
VRST Reset Threshold Voltage*
TA = 25°C VRN-1% VRN VRN+1% V
VRN-2.5% VRN VRN+2.5% V
TA = -40~85°C
xxxL 4.514 4.63 4.746
V
xxxM 4.271 4.38 4.490
xxxT 3.003 3.08 3.157
xxxS 2.857 2.93 3.003
xxxR 2.564 2.63 2.696
xxxZ 2.262 2.32 2.378
xxxY 2.145 2.20 2.255
VRTH Reset Threshold Hysteresis* VCC varries between VRN ±5% 50 mV
VOH Output High Voltage
VCC ≥ 4.5V Isource=800uA VCC-1.5
V
VCC ≥ 2.7V Isource=500uA
0.8xVCC
VCC ≥ 1.8V Isource=150uA
VCC ≥ 1.0V Isource=40uA
VOL Output Low Voltage
VCC ≥ 4.5V Isink=3.2mA 0.4
VVCC ≥ 2.7V Isink=1.2mA 0.3
VCC ≥ 1.0V Isink=100uA 0.3
ILKG Open-Drain Ouput Leakage
Current VCC > VTH(MAX) for PI4S803 1 uA
VPFT PFI Input Threshold VPFI varies from 1.5V and 1.0V 1.2 1.25 1.3 V
IPFI PFI Input Leakage Current ±25 nA
4P-0.2 02/24/05
PI4S809/803
µP Supervisor Circuits
ADVANCE INFORMATION, COMPANY CONFIDENTIAL
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 1.12 1.6 2.25 s
tMR MR Pulse Width 1 μs
tMD MR to RESET Output Delay VCC = 5.0V 250 ns
tWP WDI Pulse Width 50 ns
AC Electrical Characteristics
Watchdog Timing Diagram
V
CC
RESET
RESET
WDI
MR
t
RS
V
RST
V
RST
t
WD
t
RS
t
MD
t
MR
t
WP
t
RS
5P-0.2 02/24/05
PI4S809/803
µP Supervisor Circuits
ADVANCE INFORMATION, COMPANY CONFIDENTIAL
Packaging Mechanical: 3-pin SOT-23
X.XX
X.XX
DENOTES DIMENSIONS
IN MILLIMETERS
Note:
1) Controlling dimensions in millimeters.
2) Ref: JDDEC TO-236AB
0.45
0.60
1.80
2.00
1.20
1.40
2.20
2.64
0.90
1.12
0.013
0.102
0.09
0.18
0.55
0.95
0.38
0.51
0-8
o
2.80
3.04
Ordering Information
Notes:
1. Thermal characteristics can be found on the company web site at www.pericom.com/packaging/
Ordering Code Package Code Package Description
PI4S809xW W 3-pin, SOT-23
PI4S803xW W 3-pin, SOT-23
Pericom Semiconductor Corporation • 1-800-435-2336 • www.pericom.com
Marking Information
1 2 3 4
CODE DESCRIPTION
1 2 Part Number
3 Year
4 Work Week
Part Number Code
Code 1 2 Part No. Code 1 2 Part No.
AA PI4S809L BC PI4S803L
AB PI4S809M BD PI4S803M
AC PI4S809T BE PI4S803T
AD PI4S809S BF PI4S803S
AE PI4S809R BG PI4S803R
AF PI4S809Z BH PI4S803Z
AG PI4S809Y BI PI4S803Y