R
EM6151/52
Copyright
2005, EM Microelectronic-Marin SA
Subject to change without notice
Rev. A, 08/05
Phone: +41.32.755-5111, Fax: +41.32.755-5403
www.emmicroelectronic.com
info@emmicroelectronic.com
Windowed Watchdog IC with 5V LDO
Description
The EM6151/52 are microprocessor voltage supervisory
circuits including voltage monitoring, reset timeout period
and windowed watchdog. Moreover, the EM6152 includes a
5V low-dropout voltage regulator on-chip.
The watchdog timer, the reset timeout period and the
voltage threshold are set by external resistors.
The windowed watchdog timer function offers increased
security compared to a standard watchdog timer.
Benefits
Greatly improves security:
Prevents endless loops
Reinitializes the system in case of SW code errors
Avoids conflict between master and slaves MCUs
Catches a malfunctioning crystal oscillator
Increased flexibility:
Short or long ratio for opened/closed watchdog
window
Parameters set by external resistors
Detects events that are expected within a time interval
that has both a minimum and a maximum
Better heat dissipation (EM6152)
One-chip solution to reduce drastically PCB size and
mounting costs (EM6152)
Windowed Watchdog
A sophisticated watchdog timer detects when the processor
is running outside of an expected (opened) window of
operation. A reset is asserted whenever a TCL is not
received while the watchdog window is opened. Two ratios
for the opened/closed windows are available: 33%/67% for
increased security or 67%/33% for increased programming
flexibility.
Closed
Closed
Closed
Closed
Opened
Opened
Opened
TCL incorrect - too fast RES will go active:
TCL incorrect - too slow RES will go active:
t
TCL correct RES will NOT go active:
3 correct TCL service EN goes active:
Window:
Features
Windowed watchdog function
Voltage monitoring and power-on reset function
Separate ENABLE output for peripheral: the circuit
waits 3 acknowledgements from
P to ensure full
working system before activation of peripheral (e.g.
motor drivers, actuators)
CAN sleep mode function
-40C to +125C operating temperature
Open-drain active-low RESET output
Push-pull active-low ENABLE output
Low supply current: 35A / 145A (EM6151/52)
5V LDO Voltage Regulator, up to 400mA (EM6152)
SO-8 and PSOP-16 power package (EM6152)
High Flexibility and Accuracy
Adjustable reset threshold voltage with
3% accuracy
Adjustable watchdog timer (T
WD
= 10ms to 1sec,
accuracy
10%) using one external resistor
Adjustable reset timeout period T
POR
using one
external resistor
Typical Application
V
DD
GND
RES
R
OSC
EM6151
V
DD
I/O
RESET
MPU,MCU
GND
TCL
EN
EN
V
IN
Peripheral,
Actuator
To adjust
voltage
threshold
To adjust
T
WD
and T
POR
GND
LDO
Voltage
Regulator
5V regulated V
DD
EM6152
V
DD
Unregulated V
DD
(up to +40V)
(open-drain)
Product Offering
Part Number
LDO Voltage Regulator
(V
OUT
/ V
DROPOUT
@ I
OUT
)
Input
Voltage
Package
EM6151_SO8
-
1.2 to 5.5V
SO-8
EM6152_SO8
5V / 250mV @ 100mA 2.3 to 40V
SO-8
EM6152_PS16
5V / 250mV @ 250mA 2.3 to 40V
PSOP-16
EM MICROELECTRONIC -
MARIN SA
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