R
EM MICROELECTRONIC -
MARIN SA
EM6152
5V Automotive Regulator with Windowed Watchdog
Description
The EM6152 offers a high level of integration by combining
voltage regulation, voltage monitoring and software
monitoring using a windowed watchdog.
A comparator monitors the voltage applied at the V
IN
input
comparing it with an internal voltage reference V
REF
. The
power-on reset function is initialized after V
IN
reaches V
REF
and takes the reset output inactive after a delay T
POR
depending on external resistance R
OSC
. The reset output goes
active low when the V
IN
voltage is less than V
REF
. The
RES
and
EN
outputs are guaranteed to be in a correct state for a
regulated output voltage as low as 1.2 V. The watchdog
function monitors software cycle time and execution.
If software clears the watchdog too quickly (incorrect cycle
time) or too slowly (incorrect execution) it will cause the
system to be reset. For enhanced security, the watchdog
must be serviced within an 鈥渙pen鈥?time window. During the
remaining time, the watchdog time window is 鈥渃losed鈥?and a
reset will occur should a
TCL
pulse be received by the
watchdog during this 鈥渃losed鈥?time window. The ratio of the
open/closed window is either 33%/67% or 67%/33%.
The system ENABLE output prevents critical control functions
being activated until software has successfully cleared the
watchdog three times. Such a security could be used to
prevent motor controls being energized on repeated resets of
a faulty system.
When the microcontroller goes in stand-by mode or stops
working, no signal is received on the
TCL
input of the
EM6152 (version 55) and it goes into a stand-by mode in
order to save power (CAN-bus sleep detector).
In EM6152, the voltage regulator has a low dropout voltage
and a low quiescent current of 135
渭A.
The quiescent current
increases only slightly in dropout prolonging battery life. Built-
in protection includes a positive transient absorber for up to
45 V (load dump) and the ability to survive an unregulated
input voltage of -42 V (reverse battery). The input may be
connected to ground or to a reverse voltage without reverse
current flowing from the output to the input.
Features
Low quiescent current 135
渭A
-40擄C to +125擄C temperature range
Highly accurate 5 V, 400 mA guaranteed output (actual
maximum current depends on power dissipation)
Low dropout voltage, typically 250 mV at 250 mA
Unregulated DC input can withstand -42 V reverse battery
and +45 V power transients
Fully operational for unregulated DC input voltage up to
40 V and regulated output voltage down to 3.0 V
No reverse output current
Very low temperature coefficient for the regulated output
Current limiting
Windowed watchdog with an adjustable time windows,
guaranteeing a minimum time and a maximum time
between software clearing of the watchdog
Time base accuracy
鹵8%
(at 100ms)
Sleep mode function (V55)
Adjustable threshold voltage using external resistors
Adjustable power on reset (POR) delay using one
external resistor
Open-drain active-low RESET output
Reset output guaranteed for regulated output voltage
down to 1.2 V
System ENABLE output offers added security
Qualified according to AEC-Q100
Green SO-8 and PSOP2-16 packages (RoHS compliant)
Applications
Automotive systems
Industrial
Home security systems
Telecom / Networking
Computers
Set top boxes
Typical Operating Configuration
Unregulated
Voltage
INPUT
OUTPUT
+
100nF 22uF
Selection Table
5V
Part Number
V
DD
V
REF
Closed
Window
Open
Window
CAN-bus sleep
detector
Microprocessor
EM6152
22uF
+
R
1
EM6152
V30
EM6152
V50
EM6152
V53
EM6152
V55
1.17 V
1.52 V
1.52 V
1.275 V
67%
67%
33%
67%
33%
33%
67%
33%
R
OSC
V
IN
TCL
RES
I/O
RES
I/O
R
2
GND
No
No
No
Yes
R
OSC
V
SS
EN
Please refer to Fig. 4 for more information about the
open/closed window of the watchdog.
Fig. 1
Copyright 漏 2006, EM Microelectronic-Marin SA
rev. B / 06.06
1
www.emmicroelectronic.com
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