1
The MIC705/MIC706/MIC707/MIC708 are inexpensive
microprocessor supervisory circuits that monitor power
supplies in microprocessor based systems. The circuit
functions include a watchdog timer, microprocessor
reset, power failure warning and a debounced manual
reset input.
The MIC705 and MIC706 offer a watchdog timer
function while the MIC707 and MIC708 have an active
high reset output in addition to the active low reset
output.
Supply voltage monitor levels of 4.65V and 4.4V are
available. The MIC705/MIC707 have a nominal reset
threshold level of 4.65V while the MIC706 and MIC708
have a 4.4V nominal reset threshold level. When the
supply voltage drops below the respective reset
threshold level, RESET is asserted.
1
2
3
4
V
CC
GND
PFI
8
7
6
5
WDO
RESET
WDI
PFO
MIC705
MIC706
MR
PFO
1
2
3
4
V
CC
GND
PFI
8
7
6
5
RESET
RESET
NC
PFO
MIC707
MIC708
MR
PFO
Top View
N Package - 8 Lead Plastic DIP Package
M Package - 8 Lead Plastic SOIC Package
Part
Package
Temp. Range
MIC70_N
8-Lead PDIP
-40C to +85C
MIC70_M
8-Lead SOIC
-40C to +85C
Automotive Systems
Intelligent Instruments
Critical Microprocessor Power Monitoring
Printers
Computers
Controllers
Debounced Manual Reset Input is
TTL/CMOS Compatible
Reset Pulse Width, 200ms
Watchdog Timer, 1.6s (MIC705/MIC706)
4.4V or 4.65V Precision Voltage Monitor
Early Power Fail Warning
or Low Battery
Detect
VCC
RESET
P
RESET
VCC
MIC705
MIC706
+5V (Regulated)
MR
WDI
I/O Line
PFO
Interrupt
PFI
DC Voltage
(Unregulated)
Manual
Reset
WDO
NMI
Typical Operating Circuit
Features
Description
Pin Configuration
Ordering Information
Typical Applications
MIC705/6/7/8 P Supervisory Circuits
MIC705/6/7/8
P Supervisory Circuits
MIC705/6/7/8
P Supervisory Circuits
2
Electrical Characteristics
VCC = 4.75V to 5.5V for MIC705/MIC707, VCC = 4.5V to 5.5V for MIC706/MIC708, T
A
= -40C to 85C unless otherwise noted.
Parameter
Conditions
Min
Typ
Max
Units
Operating Voltage Range, VCC
MIC70--
1.4
5.5
V
Supply Current
MIC70--
60
A
Reset Voltage Threshold
MIC705, MIC707
4.50
4.65
4.75
V
MIC706, MIC708
4.25
4.4
4.5
Reset Threshold Hysteresis
40
mV
Reset Pulse Width, t
RS
140
200
280
ms
RESET Output Voltage
ISource = 800
A
VCC - 1.5V
V
ISink = 3.2mA
0.4
MIC70--C, ISink = 50
A, VCC = 1.4V
0.3
RESET Output Voltage
ISource = 800
A
VCC - 1.5V
V
ISink = 1.2mA
0.4
Watchdog Timeout Period, t
WD
1.0
1.6
2.25
sec
WDI Minimum Input Pulse, t
WP
VIL = 0.4V, VIH = 80% of VCC
50
ns
WDI Threshold Voltage
VIH, VCC = 5V
3.5
V
VIL, VCC = 5V
0.8
WDI Input Current
WDI = 0V
-150
-50
A
WDI = VCC
50
150
WDO Output Voltage
ISource = 800
A
VCC - 1.5V
V
ISink = 1.2mA
0.4
Absolute Maximum Ratings
Terminal Voltage
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.0V
All Other Inputs . . . . . . . . . . . . -0.3V to (VCC + 0.3V)
Input Current
VCC, Gnd. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25mA
Output Current (all outputs) . . . . . . . . . . . . . . . . . 20mA
Operating Temperature Range
MIC70_N, MIC70_M . . . . . . . . . . . . . . . . . -40C to 85C
Storage Temperature Range . . . . . . . . . . . . .-65C to 150C
Lead Temperature (Soldering - 10 sec.) . . . . . . . . . . . 300C
Power Dissipation (PDIP) . . . . . . . . . . . . . . . . . . . . 475mW
Power Dissipation (SOIC) . . . . . . . . . . . . . . . . . . . . 400mW
Stresses above those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent device failure. Functionality at or above these limits is not implied. Exposure to absolute
maximum ratings for extended periods may affect device reliability. Operating ranges define those limits between which the functionality of the device is guaranteed.
MIC705/6/7/8
P Supervisory Circuits
3
Electrical Characteristics
VCC = 4.75V to 5.5V for MIC705/MIC707, VCC = 4.5V to 5.5V for MIC706/MIC708, T
A
= -40C to 85C unless otherwise noted.
Parameter
Conditions
Min
Typ
Max
Units
MR Pull-Up Current
MR = 0V
100
250
600
A
MR Pulse Width, t
MR
150
nS
MR Input Threshold
VIL
0.8
V
VIH
2.0
MR to Reset Output Delay, t
MD
250
nS
PFI Input Threshold
VCC = 5V
1.2
1.25
1.3
V
PFI Input Current
-25
0.01
+25
nA
PFO Output Voltage
ISink = 3.2mA
0.4
V
VCC = 5V, ISource = 800
A
VCC - 1.5V
4
Manual Reset Input forces RESET to assert when pulled below 0.8V.
An internal pull-up current of 250
A on this input forces it high when left
floating. This input can also be driven from TTL or CMOS logic.
Primary supply input, +5V.
IC ground pin, 0V reference.
Power fail input. Internally connected to the power fail comparator
which is referenced to 1.25V. The power fail output (PFO) remains
high if PFI is above 1.25V. PFI should be connected to GND or VOUT
if the power fail comparator is not used.
Power fail output. The power fail comparator is independent of all other
functions on this device.
Watchdog input. The WDI input monitors microprocessor activity, an
internal watchdog timer resets itself with each transition on the
watchdog input. If the WDI pin is held high or low for longer than the
watchdog timeout period, WDO is forced to active low. The watchdog
function can be disabled by floating the WDI pin.
No Connect
RESET is asserted if either VCC goes below the reset threshold or by a
low signal on the manual reset input (MR). RESET remains asserted
for one reset timeout period (200ms) after VCC exceeds the reset
threshold or after the manual reset pin transitions from low to high. The
watchdog timer will not assert RESET unless WDO is connected to
MR.
Output for the watchdog timer. The watchdog timer resets itself with
each transition on the watchdog input. If the WDI pin is held high or
low for longer than the watchdog timeout period, WDO is forced low.
WDO will also be forced low if VCC is below the reset threshold and
will remain low until VCC returns to a valid level.
RESET is the compliment of RESET and is asserted if either VCC goes
below the reset threshold or by a low signal on the manual reset input
(MR). RESET is suitable for microprocessors systems that use an
active high reset.
Pin No.
MIC705
MIC707
Pin Name
MIC706
MIC708
MR
1
1
VCC
2
2
GND
3
3
PFI
4
4
PFO
5
5
WDI
6
N/A
N/C
N/A
6
RESET
7
7
WDO
8
N/A
RESET
N/A
8
Pin Functions
MIC705/6/7/8
P Supervisory Circuits
5
+
-
4.65V*
RESET
GENERATOR
+
-
1.25V
WATCHDOG
TIMER
VCC (2)
MR (1)
PFO (5)
RESET (7)
WDO (8)
WDI (6)
PFI (4)
VCC
250A
+
-
4.65V*
RESET
GENERATOR
+
-
1.25V
VCC (2)
MR (1)
PFO (5)
RESET (7)
PFI (4)
VCC
RESET (8)
250
A
Figure 1. MIC705/MIC706 Block Diagram
Figure 2. MIC707/MIC708 Block Diagram
Block Diagram
* 4.4V for MIC706
* 4.4V for MIC708
MIC705/6/7/8
P Supervisory Circuits
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