MIC705/706/707/708
µP Supervisory Circuit
General Description
The MIC705, MIC706, MIC707, and 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 and 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.
Datasheets and support documentation are available on
Micrel’s web site at:
www.micrel.com.
Features
•
Debounced manual reset input is TTL/CMOS
compatible
•
Reset pulse width: 200ms
•
Watchdog timer: 1.6s (MIC705/706)
•
4.65V or 4.40V precision voltage monitor
•
Early power-fail warning or low-battery detect
Applications
•
•
•
•
•
•
Automotive systems
Intelligent systems
Critical microprocessor power monitoring
Battery-powered computers
Computers
Controllers
Typical Application
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 •
http://www.micrel.com
September 15, 2014
Revision 2.1
Micrel, Inc.
MIC705/706/707/708
Ordering Information
Part Number
MIC705MY
MIC706MY
MIC707MY
MIC708MY
Threshold (V)
4.65
4.40
4.65
4.40
/RESET
√
√
√
√
√
√
RESET
WDI
√
√
Junction Temperature Range
−40°C
to +85°C
−40°C
to +85°C
−40°C
to +85°C
−40°C
to +85°C
Package
8-Pin SOIC
8-Pin SOIC
8-Pin SOIC
8-Pin SOIC
Pin Configuration
MIC705/706
8-Pin SOIC (M)
(Top View)
MIC707/708
8-Pin SOIC (M)
(Top View)
Pin Description
Pin Number
MIC706
1
2
3
Pin Number
MIC708
1
2
3
Pin Name
Pin Name
Manual reset input forces /RESET to assert when pulled below 0.8V. An internal
pull-up current of 250µA 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 VCC if the power-fail comparator is not
used.
Power-Fail Output: The power-fail comparator is independent of all other function
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.
Not internally connected.
/MR
VCC
GND
4
4
PFI
5
5
/PFO
6
N/A
WDI
N/A
6
N/C
September 15, 2014
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Revision 2.1
Micrel, Inc.
MIC705/706/707/708
Pin Description (Continued)
Pin Number
MIC706
Pin Number
MIC708
Pin Name
Pin Name
/RESET is asserted if either VCC goes below the reset threshold voltage or by low
signal on the manual reset input (/MR). /RESET remains asserted for one reset
timeout period (200ms) after VCC exceeds the reset threshold voltage or after the
manual reset pin transition 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
to 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 voltage 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 voltage or by a low signal on the manual reset input (/MR). RESET
is suitable for microprocessor systems that use active high reset.
7
7
/RESET
8
N/A
/WDO
N/A
8
RESET
September 15, 2014
3
Revision 2.1
Micrel, Inc.
MIC705/706/707/708
Absolute Maximum Ratings
(1)
Terminal Voltage
VCC .......................................................
−0.3V
to +6.0V
All Other Inputs. ...........................
−0.3V
to (V
CC
+ 0.3V)
Input Current
VCC, GND ............................................................ 25mA
Output Current (All) ..................................................... 20mA
Lead Temperature (soldering, 10s) ............................ 300°C
Storage Temperature (T
S
) .........................
−65°C
to +150°C
Operating Ratings
(2)
Operating Temperature Range ................... –40°C to +85°C
Power Dissipation (SOP) ......................................... 400mW
Thermal Resistance
8-Pin SOIC....................................................... 150°C/W
Electrical Characteristics
(3)
V
CC
= 4.75V to 5.5V for MIC705/707; V
CC
= 4.5V to 5.5V for MIC706/708; T
A
= Operating Temperature Range,
bold
values indicate –40°C ≤ T
A
≤ +85°C, unless noted.
Parameter
Operating Voltage Range
Supply Current
Reset Voltage Threshold
Reset Threshold Hysteresis
Reset Pulse Width (t
RS
)
/RESET Output Voltage
I
SOURCE
= 800µA
I
SINK
= 3.2mA
I
SOURCE
= 800µA
I
SINK
= 1.2mA
1.0
V
IL
= 0.4V, V
IH
= 80% of V
CC
V
IH
, V
CC
= 5V
V
IL
, V
CC
= 5V
WDI = 0V
WDI = V
CC
I
SOURCE
= 800µA
I
SINK
= 1.2mA
/MR = 0V
100
250
V
CC
−
1.5V
0.4
600
−150
−50
50
150
50
3.5
0.8
1.6
V
CC
−
1.5V
0.4
2.25
140
V
CC
−
1.5V
0.4
MIC705, MIC707
MIC706, MIC708
4.50
4.25
4.65
4.4
40
200
280
Condition
Min.
1.4
Typ.
Max.
5.5
60
4.75
4.5
Units
V
µA
V
mV
ms
V
RESET Output Voltage
Watchdog Timeout Period (t
WD
)
WDI Minimum Input Pulse (t
WP
)
WDI Threshold Voltage
V
s
ns
V
WDI Input Current
µA
WDO Output Voltage
/MR Pull-Up Current
Notes:
V
µA
1. Exceeding the absolute maximum ratings may damage the device.
2. The device is not guaranteed to function outside its operating ratings.
3. Specification for packaged product only
September 15, 2014
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Revision 2.1
Micrel, Inc.
MIC705/706/707/708
Electrical Characteristics
(3)
(Continued)
V
CC
= 4.75V to 5.5V for MIC705/707; V
CC
= 4.5V to 5.5V for MIC706/708; T
A
= Operating Temperature Range,
bold
values indicate –40°C ≤ T
A
≤ +85°C, unless noted.
Parameter
/MR Pulse Width (t
MR
)
/MR Input Threshold
/MR-to-Reset Output Delay (t
MD
)
PFI Input Threshold
PFI Input Current
/PFO Output Voltage
I
SINK
= 3.2mA
V
CC
= 5V, I
SOURCE
= 800µA
V
CC
−
1.5V
V
CC
= 5V
1.2
−25
1.25
0.01
V
IL
V
IH
2.0
250
1.3
+25
0.4
Condition
Min.
150
0.8
Typ.
Max.
Units
ns
V
ns
V
nA
V
September 15, 2014
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Revision 2.1
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