MIC706P/R/S/T, MIC708R/S/T
Micrel, Inc.
MIC706P/R/S/T, MIC708R/S/T
µP Supervisory Circuit
General Description
The MIC705, MIC706, MIC707, and MIC708 are inexpensive
mircoprocessor supervisory circuit that monitors power sup-
plies in microprocessor based systems. The circuit functions
include a watchdog timer, microprocessor reset, backup
battery switchover, 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
threshold level. When the supply voltage drops below the
respective reset threshold level, /RESET is asserted.
Features
• 30µA Maximum Supply Current
• Debounced manual reset input is TTL/CMOS
Compatible
• Reset Pulse Width, 200ms
• Watchdog timer, 1.6s (MIC706)
• Precision supply voltage monitor
• Early power fail warning or low battery detect
Applications
•
•
•
•
•
•
Laptop computers
Intelligent systems
Critical microprocessor power monitoring
Printers
Computers
Controllers
Ordering Information
Part Number
Standard
MIC70_ _N
MIC70_ _M
Pb-Free
MIC70_ _NY
MIC70_ _MY
Temperature Range
–40ºC to +85ºC
–40ºC to +85ºC
Package
8-Pin PDIP
8-Pin SOIC
Typical Application
+3.0 or +3.3V (Regulated)
Manual
Reset
VCC
MR
RESET
VCC
RESET
µP
I/O Line
NMI
Interrupt
MIC706
DC Voltage
(Unregulated)
PFI
WDI
WDO
PFO
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
January 2006
1
MIC706P/R/S/T, MIC708R/S/T
MIC706P/R/S/T, MIC708R/S/T
Micrel, Inc.
Pin Configuration
MR
V
CC
GND
PFI
1
2
3
4
8
WDO
RESET
(RESET for MIC706P)
WDI
MIC706
7
6
5
PFO
MR
V
CC
GND
PFI
1
2
3
4
8
RESET
RESET
NC
MIC708
7
6
5
PFO
8-Pin PDIP Package
8-Pin SOIC Package
Pin Description
Pin Number
MIC705/6
1
Pin Number
MIC707/8
1
Pin Name
/MR
Pin Function
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 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.
Watch Dog Input. The WDI input monitors microprcessor activity, an internal
watchdog timer resets itself with each transition on the watchdog input. If the
WDIpin is held high or low for longer than the watchog timeout period, /WDO
is forced to active low. the watchdog function can be diabled by floating the
WDI pin.
Not Internally Connected
/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 V
CC
exceeds the reset threshold volt-
age 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 o 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 id V
CC
is below the reset threshold voltageand will remain low
until V
CC
returns to a valid level.
2
3
4
2
3
4
VCC
GND
PFI
5
6
5
N/A
/PFO
WDI
N/A
7
6
7
N/C
/RESET
8
N/A
/WDO
N/A
8
RESET
RESET is the compliment of /RESET and is asserted if either V
CC
goes be-
low 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.
MIC706P/R/S/T, MIC708R/S/T
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January 2006
MIC706P/R/S/T, MIC708R/S/T
Micrel, Inc.
Absolute Maximum Ratings
(1)
Terminal Voltage
V
CC
..........................................................–0.3V to +6.0V
All other inputs .............................–0.3V to (V
OUT
+ 0.3V)
Input Current
V
CC
, Gnd ................................................................ 25mA
Output Current (all outputs) ........................................ 20mA
Lead Temperature (soldering, 10 sec.) ...................... 300°C
Storage Temperature ................................ –65°C to +150°C
Operating Ratings
(2)
Operating Temperature Range
MIC70_N ................................................ –40°C to +85°C
MIC70_M ................................................ –40°C to +85°C
Power Dissipation (PDIP) ........................................ 475mW
Power Dissipation (SOP) ......................................... 400mW
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, V
CC
Supply Current
Reset Voltage Threshold
MIC70_P/R
MIC70_S
MIC70_T
2.55
2.85
3.00
140
I
Source
= 200µA
I
Sink
= 1.2mA
I
Sink
= 50µA, V
CC
= 1.4V
I
Source
= 200µA
I
Sink
= 1.2mA
I
Source
= 200µA
I
Sink
= 500µA
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
V
CC
= 4.5V
V
IL
V
IH
0.8 × V
CC
2.63
2.93
3.08
20
200
280
0.3
0.3
0.3
0.3
1.6
2.25
Conditions
Min.
1.4
Typ.
Max
5.5
30
2.70
3.00
3.15
Units
V
µA
V
V
V
mV
ms
V
V
V
V
V
V
V
sec
ns
ns
0.6
1
0.3
250
600
V
V
µA
V
V
µA
ns
ns
0.6
750
1.2
-25
I
Sink
= 1.2mA
I
Source
= 200µA
0.8 × V
CC
1.25
0.01
1.3
+25
0.3
V
V
ns
V
nA
V
V
Reset Threshold Hysteresis
Reset Pulse Width, t
RS
/RESET Output Voltage
(MIC70_R/S/T)
RESET Output Voltage
(MIC706P)
RESET Output Voltage
(MIC708R/S/T)
Watchdog Timeout Period, t
WD
WDI Minimum Input Pulse, t
WP
WDI Threshold Voltage
WDI Input Current
WDO Output Voltage
/MR Pull-Up Current
/MR Pulse Width, t
MR
/MR Input Threshold
/MR to Reset Output Delay, t
MD
PFI Input Threshold
PFI Input Current
/PFO Output Voltage
Note 1.
Note 2.
Note 3.
0.8 × V
CC
0.8 × V
CC
1.0
100
50
0.7 × V
CC
-1
0.8 × V
CC
20
500
150
0.7 × V
CC
Exceeding the absolute maximum rating may damage the device.
The device is not guaranteed to function outside its operating rating.
Specification for packaged product only.
January 2006
3
MIC706P/R/S/T, MIC708R/S/T
MIC706P/R/S/T, MIC708R/S/T
Micrel, Inc.
Timing Diagram
Timing Diagram for Reset
MIC706P/R/S/T, MIC708R/S/T
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January 2006
MIC706P/R/S/T, MIC708R/S/T
Micrel, Inc.
Block Diagram
VCC
250•A
MR (1)
VCC (2)
+
VTHR*
RESET
GENERATOR
-
RESET (7)
(RESET for MIC706P)
WDO (8)
WDI (6)
WATCHDOG
TIMER
PFI (4)
+
1.25V
-
PFO (5)
* 2.63, 2.93, or 3.08V
MIC705/MIC706 Block diagram
•
V THR
* 2.63, 2.93, or 3.08V
MIC707/MIC708 Block Diagram
January 2006
5
MIC706P/R/S/T, MIC708R/S/T
嵌入式系统
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