MIC706P/R/S/T, MIC708R/S/T
µP Supervisory Circuit
General Description
The MIC706 and MIC708 are inexpensive microprocessor
supervisory circuits that monitor power supplies in 3.0V
and 3.3V microprocessor-based systems. The circuit
functions include a watchdog timer, microprocessor reset,
power-failure warning, and a debounced manual reset
input.
The MIC706 offers a watchdog timer function, while the
MIC708 has an active-high reset output in addition to the
active-low reset output.
The R, S, and T versions are similar in all respects except
for supply voltage reset threshold levels. The threshold
levels are 2.63, 2.93, and 3.08V, respectively. When the
supply voltage drops below the reset threshold level,
/RESET (and RESET for the MIC708) is asserted.
The MIC706P is identical to the MIC706R, except that the
Reset output is asserted high.
Datasheets and support documentation are available on
Micrel’s web site at:
www.micrel.com.
Features
•
Maximum supply current: 30µA
•
Debounced manual reset input is TTL/CMOS
compatible
•
Reset pulse width: 200ms
•
Watchdog timer: 1.6s (MIC706)
•
Precision supply voltage monitor
•
Easy power-fail warning or low-battery detect
Applications
•
•
•
•
•
Laptop and desktop computers
Intelligent systems
Critical microprocessor power monitoring
Printers
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
May 28, 2014
Revision 2.0
Micrel, Inc.
MIC706P/R/S/, MIC708R/S/T
Ordering Information
Part Number
MIC706PMY
MIC706RMY
MIC706SMY
MIC706TMY
MIC708RMY
MIC708SMY
MIC708TMY
Threshold (V)
2.63
2.63
2.93
3.08
2.63
2.93
3.08
√
√
√
√
√
√
√
√
√
/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
–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
8-Pin SOIC
8-Pin SOIC
8-Pin SOIC
Pin Configuration
MIC706
8-Pin SOIC (M)
(Top View)
MIC708
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 outputs 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 V
OUT
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
May 28, 2014
2
Revision 2.0
Micrel, Inc.
MIC706P/R/S/, MIC708R/S/T
Pin Description (Continued)
Pin Number
MIC706
Pin Number
MIC708
Pin Name
Pin Name
/RESET is asserted if either V
CC
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
7
(MIC706P)
8
RESET
May 28, 2014
3
Revision 2.0
Micrel, Inc.
MIC706P/R/S/, MIC708R/S/T
Absolute Maximum Ratings
(1)
Terminal Voltage
V
CC
.........................................................
−0.3V
to +6.0V
All Other Inputs. ...........................
−0.3V
to (V
CC
+ 0.3V)
Input Current
V
CC
, 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
= 2.70V to 5.5V for MIC70_P/R; V
CC
= 3.00V to 5.5V for MIC70_S; V
CC
= 3.15V to 5.5V for MIC70_T.
T
A
= Operating Temperature Range,
bold
values indicate –40°C ≤ T
A
≤ +85°C, unless noted.
Parameter
Operating Voltage Range
Supply Current
MIC70_P/R
Reset Voltage Threshold
MIC70_S
MIC70_T
Reset Threshold Hysteresis
Reset Pulse Width (t
RS
)
I
SOURCE
= 200µA
/RESET Output Voltage (MIC70_R/S/T)
I
SINK
= 1.2mA
I
SINK
= 50µA, V
CC
= 1.4V
RESET Output Voltage (MIC706P)
I
SOURCE
= 200µA
I
SINK
= 1.2mA
I
SOURCE
= 200µA
I
SINK
= 500µA
1.0
V
IL
= 0.4V, V
IH
= 80% of V
CC
V
IL
= 0.4V, V
IH
= 80% of V
CC
>
4.5V
V
IH
V
IL
WDI = 0V or V
CC
I
SOURCE
= 200µA
I
SINK
= 500µA
/MR = 0V
20
250
−1
0.8 × V
CC
0.3
600
100
50
0.7 × V
CC
0.6
1
1.6
0.8 × V
CC
0.3
2.25
0.8 × V
CC
0.3
140
0.8 × V
CC
0.3
0.3
V
V
2.55
2.85
3.00
2.63
2.93
3.08
20
200
280
Condition
Min.
1.4
Typ.
Max.
5.5
30
2.70
3.00
3.15
mV
ms
V
Units
V
µA
RESET Output Voltage (MIC708R/S/T)
Watchdog Timeout Period (t
WD
)
WDI Minimum Input Pulse (t
WP
)
V
s
ns
WDI Threshold Voltage
WDI Input Current
WDO Output Voltage
/MR Pull-Up Current
Notes:
V
µA
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.
May 28, 2014
4
Revision 2.0
Micrel, Inc.
MIC706P/R/S/, MIC708R/S/T
Electrical Characteristics
(3)
(Continued)
V
CC
= 2.70V to 5.5V for MIC70_P/R; V
CC
= 3.00V to 5.5V for MIC70_S; V
CC
= 3.15V to 5.5V for MIC70_T.
T
A
= Operating Temperature Range,
bold
values indicate –40°C ≤ T
A
≤ +85°C, unless noted.
Parameter
/MR Pulse Width (t
MR
)
Condition
V
CC
>
4.5V
V
IL
V
IH
0.7 × V
CC
750
1.2
−25
I
SINK
= 1.2mA
I
SOURCE
= 200µA
0.8 × V
CC
1.25
0.01
1.3
+25
0.3
Min.
500
150
0.6
Typ.
Max.
Units
ns
/MR Input Threshold
/MR-to-Reset Output Delay (t
MD
)
PFI Input Threshold
PFI Input Current
/PFO Output Voltage
V
ns
V
nA
V
May 28, 2014
5
Revision 2.0
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