UM706xS/UM708xS
Supply Voltage Supervisor w/Watchdog Input and Manual Reset
UM706xS
SOP8
UM708xS
SOP8
General Description
The UM706xS/UM708xS series are cost effective system power supply supervisory circuits
designed to monitor the power supplies in digital systems.
The UM706xS provides power-supply monitoring circuitry that generates a reset output during
power-up, power-down, and brownout conditions. The reset output remains operational with V
CC
as low as 1V. Independent watchdog monitoring circuitry is also provided. This is activated if the
watchdog input has not been toggled within 1.6 seconds. In addition, there is a 1.25V threshold
detector for power-fail warning, low battery detection, or to monitor an additional power supply.
An active low debounced manual reset input is also included.
The UM708xS is the same as the UM706xS, except an active-high reset is substituted for the
watchdog timer. All parts are available in a small outline SOP8 package.
Applications
Applications using DSPs, Microcontrollers
or Microprocessors
Programmable Controls
Computers
Embedded System
Industrial Equipments
Intelligent Instrument
Wireless Communications Systems
Features
Wide Operation Voltage Range of 1V to 5.5V
Correct Logic Output Guaranteed to
V
CC
=1.0V
Precision Supply-Voltage Monitor: 2.63V,
2.93V, 3.08V,4.38V,4.63V
200ms Reset Pulse Width
Independent Watchdog Timer-1.6s Timeout
(UM706xS)
Active-high Reset Output (UM708xS)
Voltage Monitor for Power-Fail or
Low-Battery Warning
Temperature Range: -40° to +85°
C
C
Supply Current of 80μA (Typ.)
Pin Configurations
Top View
MR
V
CC
1
2
8
7
6
5
WDO(RESET)*
RESET
WDI(NC)*
PFO
8
7
6
5
GND 3
PFI
4
UM706(708)*
XS
XX
1
2
3
4
UM706xS
( )* for UM708xS
XX: Week Code
( )* for UM708xS
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UM706xS/UM708xS
Ordering Information
Part Number
UM706LS
UM706MS
UM706TS
UM706SS
UM706RS
UM708LS
UM708MS
UM708TS
UM708SS
UM708RS
Top
Marking
UM706LS
UM706MS
UM706TS
UM706SS
UM706RS
UM708LS
UM708MS
UM708TS
UM708SS
UM708RS
RESET
Threshold (V)
4.63
4.38
3.08
2.93
2.63
4.63
4.38
3.08
2.93
2.63
Timeout Period
(ms)
240
240
240
240
240
240
240
240
240
240
Package Type
SOP8
Typical Application Circuit
Vcc
μP
Vcc
Vcc
RESET
RESET
I/O
NMI
INT
UM706
PFI
MR
PUSHBUTTON
SWITCH
WDI
WDO
PFO
Figure 1. UM706xS Application Circuit
Vcc
μP
Vcc
Vcc
RESET
RESET
PFI
MR
PUSHBUTTON
SWITCH
RESET
RESET
UM708
PFO
INT
Figure 2. UM708xS Application Circuit
________________________________________________________________________
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UM706xS/UM708xS
Pin Description
Pin
Number
1
Pin Name
_______
Function
Manual-Reset Input triggers a reset pulse when pulled below
0.8V. This active-low input has an internal 250μA pull-up
current. It can be driven from a TTL or CMOS logic line as
well as shorted to ground with a switch.
Supply Input
Ground Reference for all signals.
Power-Fail Voltage Monitor Input. When PFI is less than
________
1.25V, PFO goes low. Connect PFI to GND or V
CC
when
not used.
Power-Fail Output goes low and sinks current when PFI is
________
less than 1.25V; otherwise PFO stays high.
Watchdog Input. If WDI remains either high or low for
__________
MR
2
3
4
V
CC
GND
PFI
________
5
PFO
UM706
6
WDI
longer than the watchdog timeout period, the WDO goes
low. The timer resets with each transition at the WDI input.
Either a high-to-low or a low-to-high transition clears the
counter. The internal timer is also cleared whenever reset is
asserted.
No Connect
Active-Low Reset Output pulses low for 200ms when
trigged, and stays low whenever V
CC
is below the reset
threshold. It remains low for 200ms after V
CC
rises above the
_______
reset threshold or MR goes from Low to High.
Watchdog Output pulls low when the internal watchdog timer
finishes its 1.6sec count and does not go high again until the
___________
UM708
NC
7
______________
RESET
UM706
8
___________
WDO
watchdog is cleared. WDO also goes low during low-line
conditions. Whenever V
CC
is below the reset threshold,
___________
______________
___________
WDO stays low; however, unlike RESET, WDO does not
have a minimum pulse width. As soon as V
CC
rises above the
___________
reset threshold, WDO goes high with no delay.
____________
UM708
RESET
Active-High Reset Output is the inverse of RESET .
____________
Whenever RESET is high, RESET is low, and vice versa.
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UM706xS/UM708xS
Absolute Maximum Ratings (Note 1)
Symbol
V
CC
Supply Voltage
____________
Parameter
Value
-0.3 to +6.0
-0.3 to V
CC
+0.3
20
20
100
471
-40 to +105
-65 to +150
Unit
V
V
mA
mA
V/μs
mW
°
C
°
C
I
CC
I
O
P
D
T
J
T
STG
RESET,
RESET
(push-pull)
Input Current, V
CC
____________
Output Current, RESET,
RESET
Rate of Rise, V
CC
Continuous Power Dissipation
Operating Junction Temperature
Storage Temperature Range
Lead Temperature (soldering, 10s)
300
°
C
Note 1: Stresses beyond those listed under “Absolute maximum Ratings” may cause permanent
damage to the device.
Electrical Characteristics
V
CC
= full range, T
A
= -40° to +85° unless otherwise noted. Typical values are at T
A
=+25°
C
C,
C,
V
CC
= 5V for L/M versions, V
CC
= 3.3V for T/S versions, and V
CC
= 3V for R version. (Note 2)
Symbol
V
CC
I
CC
Parameter
V
CC
Range
Supply
Current
Conditions
T
A
=0℃ to + 70℃
T
A
=-40℃ to + 85℃
T
A
=-40℃ to + 85℃
UM706L/
UM708L
UM706M/
UM708M
UM706T/
UM708T
UM706S/
UM708S
UM706R/
UM708R
T
A
=+25℃
T
A
=-40℃ to + 85℃
T
A
=+25℃
T
A
=-40℃ to + 85℃
T
A
=+25℃
T
A
=-40℃ to + 85℃
T
A
=+25℃
T
A
=-40℃ to + 85℃
T
A
=+25℃
T
A
=-40℃ to + 85℃
Min.
1.0
1.2
Typ.
Max.
5.5
5.5
Unit
V
μA
80
4.56
4.50
4.31
4.25
3.04
3.00
2.89
2.85
2.59
2.55
4.63
4.38
3.08
2.93
2.63
150
4.70
4.75
4.45
4.50
3.11
3.15
2.96
3.00
2.66
2.70
V
TH
Reset
Threshold
V
Reset
Threshold
Hysteresis
t
RS
Reset Pulse
Width
140
40
mV
200
280
ms
Note 2: Production testing done at T
A
= +25° limits over temperature guaranteed by design
C;
only.
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http://www.union-ic.com Rev.02 May.2014
4/15
UM706xS/UM708xS
Electrical Characteristics (Continued)
V
CC
= full range, T
A
= -40° to +85° unless otherwise noted. Typical values are at T
A
=+25°
C
C,
C,
V
CC
= 5V for L/M versions, V
CC
= 3.3V for T/S versions, and V
CC
= 3V for R version. (Note 2)
Symbol
Parameter
Conditions
I
SINK
=1.2mA,
(for R/S/T versions)
I
SINK
=3.2mA,
(for L/M versions)
V
CC
= 1.2V,
I
SINK
= 100µ
A
I
SOURCE
= 800µ
A
_______
Min.
Typ.
Max.
0.3
0.4
0.3
Unit
______________
V
OL
RESET /RESET
Output Voltage Low
______________
V
V
OH
RESET/
RESET
Output Voltage High
_______
V
CC
-1.5
100
150
250
600
V
µ
A
ns
V
V
250
1.30
+25
0.4
ns
V
nA
V
t
MR
MR
Pull-Up Current
_______
MR
Pulse Width
_______
MR
=0V
MR
Input Threshold,
Low
_______
0.8
2.0
MR
Input Threshold,
High
_______
t
MD
MR
to Reset Out Delay
PFI Input Threshold
PFI Input Current
________
V
CC
=5V
I
SOURCE
=800µ
A
I
SINK
=3.2mA
PFO
Output Voltage
Watchdog function for UM706
Watchdog Timeout
t
WD
Period
t
WP
WDI Pulse Width
WDI Input Threshold
Low
WDI Input Threshold
High
WDI Input Current
WDO Output Voltage
High
WDO Output Voltage
Low
1.20
-25
Vcc-1.5
1.25
0.01
1.0
V
IL
=0.4V,V
IH
=0.8Vcc
V
CC
=5V
V
CC
=5V
WDI=V
CC
WDI=0V
I
SOURCE
=800µ
A
I
SINK
=1.2mA
3.5
-150
Vcc-1.5
50
1.6
2.25
s
ns
0.8
V
V
50
-50
150
µ
A
V
0.4
V
Note 2: Production testing done at T
A
= +25° limits over temperature guaranteed by design
C;
only.
________________________________________________________________________
http://www.union-ic.com Rev.02 May.2014
5/15
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