R
EM6151
Copyright 2005, EM Microelectronic-Marin SA
1
www.emmicroelectronic.com
rev. B / 06.06
Low Power Windowed Watchdog with Reset,
Sleep Mode Functions
Description
The EM6151 offers a high level of integration by combining
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
supply 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 "open" time window. During the
remaining time, the watchdog time window is "closed" and a
reset will occur should a
TCL
pulse be received by the
watchdog during this "closed" 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
EM6151 (version 55) and it goes into a stand-by mode in
order to save power (CAN-bus sleep detector).
Features
Low quiescent current 35
A
-40C to +125C temperature range
Windowed watchdog with an adjustable time windows,
guaranteeing a minimum time and a maximum time
between software clearing of the watchdog
Time base accuracy
8% (at 100ms)
Voltage reference accuracy
3%
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 package (RoHS compliant)
Applications
Automotive
systems
Industrial
Home
security
systems
Telecom / Networking
Computers
Set top boxes
Typical Operating Configuration
Fig.
1
Selection Table
Part Number
V
REF
Closed
Window
Open
Window
CAN-bus sleep
detector
EM6151
V30
1.17
V
67%
33%
No
EM6151
V50
1.52
V
67%
33%
No
EM6151
V53
1.52
V
33%
67%
No
EM6151
V55
1.275
V
67%
33%
Yes
Please refer to Fig. 4 for more information about the
open/closed window of the watchdog.
EM MICROELECTRONIC -
MARIN SA
V
SS
GND
EM6151
RES
EN
TCL
V
IN
V
DD
Mi
cr
opr
o
c
e
ss
or
V
DD
I/O
RES
I/O
R
OSC
R
1
R
2
100nF
R
OSC
R
EM6151
Copyright 2005, EM Microelectronic-Marin SA
2
www.emmicroelectronic.com
rev. B / 06.06
Ordering Information
Note: the "+" symbol at the end of the part number means that this product is RoHS compliant (green). For version V30, please
contact EM Microelectronic.
Pin Assignment and Description
SO8 Name
Function
1
EN
Push-pull active low enable output
2
RES
Open drain active low reset output.
RES
must be pulled up to V
DD
even
if unused
3
TCL
Watchdog timer clear input signal
4 V
SS
GND
terminal
5 NC
No
connect
6 V
DD
Supply
voltage
7 R
OSC
R
OSC
input for RC oscillator tuning
8 V
IN
Voltage comparator input
Block Diagram EM6151
RES
EN
TCL
Voltage
Reference
Current
Controlled
Oscillator
-
+
V
REF
Comparator
Reset
Control
Timer
Enable
Logic
V
IN
R
OSC
Open drain
output RES
Fig. 2
Part Number
Version
V
REF
Package
Delivery
Form
Package
Marking
EM6151V30SO8A+
Stick, 97 pcs
EM6151V30SO8B+
V30 1.17
V
SO-8
Tape & Reel, 2500 pcs
6151030
EM6151V50SO8A+
Stick, 97 pcs
EM6151V50SO8B+
V50 1.52
V
SO-8
Tape & Reel, 2500 pcs
6151050
EM6151V53SO8A+
Stick, 97 pcs
EM6151V53SO8B+
V53 1.52
V
SO-8
Tape & Reel, 2500 pcs
6151053
EM6151V55SO8A+
Stick, 97 pcs
EM6151V55SO8B+
V55 1.275
V
SO-8
Tape & Reel, 2500 pcs
6151055
V
SS
R
OSC
4
V
DD
NC
RES
EN
TCL
V
IN
SO8
1
3
2
8
6
7
5
EM6151
R
EM6151
Copyright 2005, EM Microelectronic-Marin SA
3
www.emmicroelectronic.com
rev. B / 06.06
Absolute Maximum Ratings
Parameter Symbol
Conditions
Max. voltage at V
DD
V
DDMAX
V
SS
+ 7.0V
Max. voltage at any signal pin
V
MAX
V
DD
+ 0.3V
Min. voltage at any signal pin
V
MIN
V
SS
0.3V
Storage temperature
T
STO
-65 to +150 C
ESD
According to MIL-STD-883C
method 3015.7
V
Smax
2000V
Table 1
Stresses above these listed maximum ratings may cause
permanent damages to the device. Exposure beyond
specified operating conditions may affect device reliability or
cause malfunction.
Handling Procedures
This device has built-in protection against high static
voltages or electric fields; however, it is advised that normal
precautions be taken as for any other CMOS component.
Unless otherwise specified, proper operation can only occur
when all terminal voltages are kept within the voltage range.
At any time, all inputs must be tied to a defined logic voltage
level.
Operating Conditions
Parameter
Symbol Min. Max.
Units
Operating junction
temperature
T
j
-40
+125
C
Supply voltage
V
DD
1.2 5.5 V
RES
and
EN
guaranteed
(note 1)
V
DD
1.2 V
Comparator input voltage
V
IN
0 V
DD
V
RC-oscillator programming R
OSC
10 1000 k
Table 2
Electrical Characteristics
V
DD
= 5.0V, T
j
= -40 to +125C, unless otherwise specified
Parameter Symbol Test
Conditions
Min.
Typ.
Max.
Units
Supply current
I
DD
R
OSC
= 100k
V
IN
and
TCL
=
V
DD
, O/P
S
1M
to V
DD
35
60
A
Supply current in standby mode and sleep
mode for V55
I
DD
R
OSC
= don't care,
TCL
= V
DD
, V
IN
= 0 V
25 50
A
RES
and
EN
V
DD
= 4.5 V, I
OL
= 8 mA
0.25
0.45
V
Output Low Voltage
V
DD
= 2.0 V, I
OL
= 4 mA
0.2
0.4
V
V
OL
V
DD
= 1.2 V, I
OL
= 0.5 mA
0.04
0.2
V
EN
V
DD
= 4.5 V, I
OH
= -1 mA
3.5
4.1
V
Output High Voltage
V
DD
= 2.0 V, I
OH
= -100
A 1.8
1.9
V
V
OH
V
DD
= 1.2 V, I
OH
= -20
A 0.9
1.05
V
TCL Input Low Level
V
IL
V
SS
0.5 V
TCL Input High Level
V
IH
2.5 V
DD
V
Leakage current
I
LI
V
SS
V
TCL
V
DD
0.05
A
Version
V30
(replaces V6130)
1.135 1.170 1.205 V
Comparator reference (note 2)
V
REF
Version V50
(replaces V6150)
1.475 1.520 1.565 V
Version
V53
1.475 1.520 1.565 V
Version
V55
(replaces V6155)
1.235 1.275 1.315 V
Comparator hysteresis (note 2)
V
HY
2
mV
V
IN
input resistance
R
VIN
100
M
Table
3
Note 1: RES must be pulled up externally to V
DD
even if it is unused. ( RES and EN are used as inputs by EM test)
Note 2: the comparator reference is the power-down reset threshold. The power-on reset threshold equals the comparator reference voltage
plus the comparator hysteresis (see Fig. 5).
R
EM6151
Copyright 2005, EM Microelectronic-Marin SA
4
www.emmicroelectronic.com
rev. B / 06.06
Timing Characteristics
V
DD
= 5.0 V, T
j
= -40 to +125
C, unless otherwise specified
Parameter Symbol Test
Conditions
Min.
Typ.
Max.
Units
Propagation delay
TCL
to Output Pins
T
DIDO
250 500 ns
V
IN
sensitivity
T
SEN
V
INhigh
=1.1
x
V
REF
, V
INlow
=0.9
x
V
REF
1 5 20
s
Watchdog Reset Pulse Period
T
WDRP
TCL
inactive
T
CW
+ T
OW
+ T
WDR
ms
Version V30
Power-on Reset delay
T
POR
R
OSC
= 116.9 k
1% 91.6
100
108.3
Closed Window Time
T
CW
74 80 85.76
Open Window Time
T
OW
37 40 42.88 ms
Watchdog Time
T
WD
92.5 100 107.2
Watchdog Reset Pulse Width if no
TCL
T
WDR
2.25 2.5 2.75
Version V50
Power-on Reset delay
T
POR
R
OSC
= 121.6 k
1% 91.6
100
108.3
Closed Window Time
T
CW
74 80 85.76
Open Window Time
T
OW
37 40 42.88 ms
Watchdog Time
T
WD
92.5 100 107.2
Watchdog Reset Pulse Width if no
TCL
T
WDR
2.25 2.5 2.75
Version V53
Power-on Reset delay
T
POR
R
OSC
= 23.2 k
1% 4.57
5.0
5.44
Closed Window Time
T
CW
9.24 10 10.77
Open Window Time
T
OW
18.48 20 21.54 ms
Watchdog Time
T
WD
18.48 20 21.54
Watchdog Reset Pulse Width if no
TCL
T
WDR
0.56 0.625 0.69
Version V55
Power-on Reset delay
T
POR
R
OSC
= 107.5 k
1% 91.6
100
108.3
Closed Window Time
T
CW
74 80 85.76
Open Window Time
T
OW
37 40 42.88
Watchdog Time
T
WD
92.5 100 107.2 ms
Watchdog Reset Pulse Width if no
TCL
T
WDR
2.25 2.5 2.75
Watchdog Reset Pulse Width in Sleep Mode
T
WDRS
R
OSC
off; R
INT
=1M
2.8 3.2 3.6
Watchdog Reset Pulse Period in Sleep Mode T
WDRPS
TCL
inactive
750
1100
1450
Table 4
For different values of T
WD
and R
OSC
, see figures 9 to 12.
Timing Waveforms
Watchdog Timeout Period
Fig. 4
T
CW
(closed window)
T
OW
(open)
T
WD
80
120
Time [ms]
Watchdog
timer reset
( V30, V50 and V55 have similar ratios for T
CW
and T
OW
)
Version V50:
T
CW
(closed)
T
OW
(open)
10
30
Time [ms]
Watchdog
timer reset
Version V53:
For R
OSC
=121.6 kOhm
For R
OSC
=23.2 kOhm
T
WD
R
EM6151
Copyright 2005, EM Microelectronic-Marin SA
5
www.emmicroelectronic.com
rev. B / 06.06
Voltage Monitoring
Fig. 5
Timer Reaction
Fig. 6
Combined Voltage and Timer Reaction
Fig. 7
1
2
3
- Watchdog timer reset
Conditions: V
IN
> V
REF
after power-up sequence
T
CW
+ T
OW
T
CW
T
OW
T
CW
+ T
OW
T
CW
+ T
OW
T
WDR
T
CW
T
TCL
T
CW
TCL
RES
EN
3 correct TCL services
EN goes active low
Timeout
T
TCL
T
SEN
T
SEN
T
SEN
T
SEN
V
HY
V
IN
V
REF
T
POR
T
POR
RES
Conditions:
V
DD
>
3V
No timeout
1
2
3
T
CW
- Watchdog timer reset
3 correct TCL services
EN goes active low
T
OW
T
POR
V
IN
V
REF
TCL
RES
EN
T
CW
+T
OW
TCL
too early
Condition:
V
DD
> 3V
T
TCL
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