UM706xS/UM708xS/UM813xS

UM706xS/UM708xS/UM813xS
Supply Voltage Supervisor w/Watchdog Input and Manual Reset
UM706xS SOP8
UM708xS SOP8
UM813xS SOP8
General Description
The UM706xS/UM708xS/UM813xS 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 VCC
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. The UM813xS is the same as the UM706xS, except RESET is provided instead
_____________
of RESET. All parts are available in a small outline SOP8 package.
Applications
Features








Applications Using DSPs, Microcontrollers
or Microprocessors
Programmable Controls
Computers
Embedded Systems
Industrial Equipments
Intelligent Instruments
Wireless Communications Systems








Pin Configurations
Wide Operation Voltage Range of 1V to
5.5V
Correct Logic Output Guaranteed to
VCC=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, UM813xS)
Active-High Reset Output (UM708xS,
UM813xS)
Voltage Monitor for Power-Fail or
Low-Battery Warning
Temperature Range: -40°C to +85°C
Supply Current of 80μA (Typ.)
Top View
8
MR
1
8 WDO
VCC
2
7
RESET
GND 3
6
WDI
4
5
PFO
PFI
UM706xS
7
6
5
UM706
XS
XX
1
2
3
4
XX: Week Code
UM706xS
SOP8
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UM706xS/UM708xS/UM813xS
Pin Configurations
Top View
8
MR
1
8 RESET
VCC
2
7
RESET
GND 3
6
NC
4
5
PFO
PFI
6
5
UM708
XS
XX
1
2
3
4
XX: Week Code
UM708xS
SOP8
UM708xS
8
MR
1
8 WDO
VCC
2
7
RESET
GND 3
6
WDI
4
5
PFO
PFI
7
7
6
5
UM813
XS
XX
1
2
3
4
XX: Week Code
UM813xS
SOP8
UM813xS
Ordering Information
Part Number
UM706LS
UM706MS
UM706TS
UM706SS
UM706RS
UM708LS
UM708MS
UM708TS
UM708SS
UM708RS
UM813LS
UM813MS
UM813TS
UM813SS
UM813RS
Top
Marking
UM706LS
UM706MS
UM706TS
UM706SS
UM706RS
UM708LS
UM708MS
UM708TS
UM708SS
UM708RS
UM813LS
UM813MS
UM813TS
UM813SS
UM813RS
RESET
Threshold (V)
4.63
4.38
3.08
2.93
2.63
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
240
240
240
240
240
Package Type
SOP8
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UM706xS/UM708xS/UM813xS
Typical Application Circuit
Vcc
μP
Vcc
Vcc
RESET
RESET
WDI
I/O
PFI
WDO
NMI
MR
PFO
INT
UM706
PUSHBUTTON
SWITCH
Figure 1. UM706xS Application Circuit
Vcc
μP
Vcc
Vcc
PFI
RESET
RESET
RESET
RESET
UM708
MR
PFO
INT
PUSHBUTTON
SWITCH
Figure 2. UM708xS Application Circuit
Vcc
μP
Vcc
Vcc
RESET
RESET
WDI
I/O
PFI
WDO
NMI
MR
PFO
INT
UM813
PUSHBUTTON
SWITCH
Figure 3. UM813xS Application Circuit
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UM706xS/UM708xS/UM813xS
Pin Description
Pin
Number
Pin Name
Function
MR
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.
2
VCC
Supply Input
3
GND
Ground Reference for all signals.
1
_______
Power-Fail Voltage Monitor Input. When PFI is less
4
5
_________
PFI
than 1.25V, PFO goes low. Connect PFI to GND or
VCC when not used.
Power-Fail Output goes low and sinks current when PFI
_________
PFO
_________
is less than 1.25V; otherwise PFO stays high.
Watchdog Input. If WDI remains either high or low for
1.6sec, the internal watchdog timer runs out and the
__________
6
UM706,
UM813
WDI
UM708
NC
UM706,
UM708
______________
RESET
WDO goes low. Floating WDI or connecting WDI to a
high-impedance three-state buffer disables the watchdog
feature. The internal watchdog timer clears whenever
reset is asserted, WDI is three-stated, or WDI sees a
rising or falling edge.
No Connect
Active-Low Reset Output pulses low for 200ms when
trigged, and stays low whenever VCC is below the reset
threshold. It remains low for 200ms after VCC rises
________
above the reset threshold or M R goes from Low to
High.
7
____________
Active-High Reset Output is the inverse of RESET .
UM813
RESET
____________
Whenever RESET is high, RESET is low, and vice
versa.
Watchdog Output pulls low when the internal watchdog
timer finishes its 1.6sec count and does not go high
___________
UM706,
UM813
___________
WDO
again until the watchdog is cleared. WDO also goes
low during low-line conditions. Whenever VCC is below
___________
the reset threshold, WDO stays low; however, unlike
______________
___________
RESET , WDO does not have a minimum pulse width.
8
___________
As soon as VCC rises above the reset threshold, WDO
goes high with no delay.
____________
Active-High Reset Output is the inverse of RESET .
UM708
RESET
____________
Whenever RESET is high, RESET is low, and vice
versa.
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UM706xS/UM708xS/UM813xS
Absolute Maximum Ratings (Note 1)
Symbol
VCC
Parameter
Supply Voltage
____________
ICC
IO
RESET, RESET (push-pull)
Input Current, VCC
Value
Unit
-0.3 to +6.0
V
-0.3 to VCC +0.3
V
20
mA
____________
Output Current, RESET, RESET
Rate of Rise, VCC
20
mA
100
V/μs
PD
Continuous Power Dissipation
471
mW
TJ
Operating Junction Temperature
-40 to +105
°C
Storage Temperature Range
-65 to +150
°C
TSTG
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
VCC = full range, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA =+25°C,
VCC = 5V for L/M versions, VCC = 3.3V for T/S versions, and VCC = 3V for R version. (Note 2)
Symbol
Parameter
VCC
VCC Range
ICC
Supply
Current
Conditions
Min.
TA=0℃ to + 70℃
1.0
5.5
TA=-40℃ to + 85℃
1.2
5.5
TA=-40℃ to + 85℃
UM706L/
UM708L/UM813L
UM706M/
UM708M/UM813M
VTH
Reset
Threshold
UM706T/
UM708T/UM813T
UM706S/
UM708S/UM813S
UM706R/
UM708R/UM813R
TA=+25℃
4.56
TA=-40℃ to + 85℃
4.50
TA=+25℃
4.31
TA=-40℃ to + 85℃
4.25
TA=+25℃
3.04
TA=-40℃ to + 85℃
3.00
TA=+25℃
2.89
TA=-40℃ to + 85℃
2.85
TA=+25℃
2.59
TA=-40℃ to + 85℃
2.55
Reset
Threshold
Hysteresis
tRS
Reset Pulse
Width
Typ.
Max.
80
150
4.63
4.70
V
μA
4.75
4.38
4.45
4.50
3.08
3.11
V
3.15
2.93
2.96
3.00
2.63
2.66
2.70
40
140
Unit
200
mV
280
ms
Note 2: Production testing done at TA = +25°C; limits over temperature guaranteed by design
only.
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UM706xS/UM708xS/UM813xS
Electrical Characteristics (Continued)
VCC = full range, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA =+25°C,
VCC = 5V for L/M versions, VCC = 3.3V for T/S versions, and VCC = 3V for R version. (Note 2)
Symbol
Parameter
_____________
VOL
RESET /RESET Output
Voltage Low
_____________
VOH
tMR
RESET /RESET
Output Voltage High
Conditions
Min.
Typ.
ISINK=1.2mA,
(for R/S/T versions)
ISINK=3.2mA,
(for L/M versions)
VCC = 1.2V,
ISINK = 100µA
ISOURCE = 800µA
_______
_______
MR Pull-Up Current
_______
MR Pulse Width
MR =0V
Max.
Unit
0.3
0.4
V
0.3
VCC-1.5
100
150
V
250
600
µA
ns
0.8
V
_______
MR Input Threshold,
Low
_______
MR Input Threshold,
High
2.0
V
_______
tMD
MR to Reset Out Delay
PFI Input Threshold
PFI Input Current
________
PFO Output Voltage
VCC=5V
ISOURCE=800µA
ISINK=3.2mA
Watchdog function for UM706/UM813
Watchdog Timeout
tWD
Period
tWP
WDI Pulse Width
VIL=0.4V, VIH=0.8Vcc
WDI Input Threshold
VCC=5V
Low
WDI Input Threshold
VCC=5V
High
WDI=VCC
WDI Input Current
WDI=0V
WDO Output Voltage
ISOURCE=800µA
High
WDO Output Voltage
ISINK=1.2mA
Low
1.20
-25
Vcc-1.5
1.25
0.01
250
1.30
+25
0.4
1.0
1.6
2.25
50
V
s
ns
0.8
3.5
-150
ns
V
nA
V
V
50
-50
150
Vcc-1.5
µA
V
0.4
V
Note 2: Production testing done at TA = +25°C; limits over temperature guaranteed by design
only.
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UM706xS/UM708xS/UM813xS
Block Diagram
WDI
WATCHDOG
TRANSITION
DETECTOR
6
WATCHDOG
TIMER
8 WDO
TIMEBASE FOR
RESET AND
WATCHDOG
VCC
250μA
MR
1
RESET
GENERATOR
VCC
2
7
RESET/
(RESET)*
+
VREF
PFI
4
+
5
PFO
1.25V
3
GND
Figure 4. UM706xS/UM813xS Block Diagram
(RESET)* for UM813xS
8 RESET
VCC
250μA
MR
1
RESET
GENERATOR
VCC
2
7 RESET
+
VREF
PFI
4
+
5
PFO
1.25V
3
GND
Figure 5. UM708xS Block Diagram
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UM706xS/UM708xS/UM813xS
Typical Operating Characteristics
_______________
_______________
RESET Output Voltage vs. Supply Voltage
RESET Response Time
(a)
(b)
2V/div
VCC
VCC
2V/div
2V/div
_____________
RESET
2V/div
_____________
RESET
1μs/div
500ms/div
Power-Fail Comparator Assertion
Response Time
Power-Fail Comparator De-assertion
Response Time
(c)
2V/div
(d)
________
PFO
2V/div
________
PFO
1V/div
1V/div
PFI
PFI
200ns/div
VCC
200ns/div
2kΩ
VCC
RESET
VCC
10kΩ
VCC
RESET
RESET
RESET
30pF
330pF
GND
GND
(a)
(b)
+5V
+5V
PFI
1kΩ
+
PFI
+
PFO
PFO
-
30pF
+1.25V
(c)
30pF
1kΩ
+1.25V
(d)
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UM706xS/UM708xS/UM813xS
Typical Operating Characteristics
RESET Output Voltage vs. Supply Voltage
RESET Response Time
(e)
2V/div
VCC
(e)
2V/div
VCC
2V/div
RESET
RESET
2V/div
500ms/div
2μs/div
______________
______________
RESET, RESET Assertion
RESET, RESET De-assertion
(f)
(f)
RESET
RESET
2V/div
2V/div
2V/div
_____________
RESET
_____________
RESET
2V/div
200ns/div
200ns/div
VCC
VCC
10kΩ
RESET
RESET
10kΩ
RESET
330pF
GND
330pF
330pF
GND
(e)
10kΩ
(f)
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UM706xS/UM708xS/UM813xS
Detailed Description
Power-Fail Reset
The reset output provides a reset signal to the microprocessor whenever the VCC input is below the
threshold. An internal timer holds the reset output active for 200ms after the voltage on V CC rises
above the threshold. This is intended as a power-on reset signal for the microprocessor. It allows
time for both the power supply and the microprocessor to stabilize after power-up. If a power
supply brownout or interruption occurs, the reset line is similarly activated and remains active for
200ms after the supply recovers. If another interruption occurs during an active reset period, the
reset timeout period continues for an additional 200ms.
The reset output is guaranteed to remain valid with VCC as low as 1V. This ensures that the
microprocessor is held in a stable shutdown condition as the power supply starts up.
______________
The UM706xS provides an active low RESET signal while the UM813xS provides an active
high RESET signal. The UM708xS has both an active high RESET output and an active low
_____________
RESET output.
Power-Fail Comparator
The power-fail comparator can be used for various purposes because its output and non-inverting
input are not internally connected. The inverting input is internally connected to a 1.25V
reference.
To build an early-warning circuit for power failure, connect the PFI pin to a voltage driver, choose
the voltage divider ratio so that the voltage at PFI falls below 1.25V just before the regulator drops
________
out. Use PFO to interrupt the µP so it can prepare for an orderly power-down.
Manual Reset
_______
The Manual-Reset input (M R ) allows reset to be trigged by a pushbutton switch. The switch is
_______
effectively debounced by the 140ms minimum reset pulse width. M R is TTL/CMOS logic
_______
compatible, so it can be driven by an external logic line. If unused, M R input can be tied high or
left floating.
Watchdog Timer
The UM706xS/UM813xS watchdog circuit monitors the μP’s activity. If the μP does not toggle
__________
the watchdog input (WDI) within 1.6sec and WDI is not three-stated, WDO goes low. As long as
_____________
RESET is asserted or the WDI input is three-stated, the watchdog timer will stay cleared and will
not count. As soon as reset is released and WDI is driven high or low, the timer will start counting.
Pulses as short as 50ns can be detected.
__________
Typically, WDO will be connected to the non-maskable interrupt input (NMI) of a μP. When VCC
__________
drops below the reset threshold, WDO will go low whether or not the watchdog timer has timed
_____________
out yet. Normally this would trigger an NMI interrupt, but RESET goes low simultaneously, and
thus overrides the NMI interrupt.
__________
If WDI is left unconnected, WDO can be used as a low-line output. Since floating WDI disables
__________
the internal timer, WDO goes low only when VCC falls below the reset threshold, thus
functioning as a low-line output.
_____________
The UM706xS has a watchdog timer and a RESET output. The UM708xS has both active-high
and active-low reset outputs. The UM813xS has both an active-high reset output and a watchdog
timer.
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UM706xS/UM708xS/UM813xS
tWP
WDI
tWD
tWD
tWD
+5V
0V
+5V
WDO
0V
+5V
RESET
RESET EXTERNALLY
TRIGGERED BY MR
0V
tRS
Figure 6. Watchdog and Reset Timing
VCC
VRT
VRT
tRS
tRS
+5V
RESET
0V
+5V
MR
0V
tMD
tMR
+5V
WDO
MR EXTERNALLY DRIVEN LOW
0V
Figure 7. Reset, Manual Reset and Watchdog Timing
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UM706xS/UM708xS/UM813xS
Applications Information
______________
Valid RESET below 1V VCC
The UM706xS/UM708xS/UM813xS are guaranteed to provide a valid reset level with VCC as low
as 1V. When VCC falls below 1V, the internal transistor does not have sufficient drive to hold it on
_____________
_____________
so the voltage on RESET is no longer held at 0V. If a pull-down resistor is added to the RESET
pin as shown in Figure 8, any stray charge or leakage current will be drained to ground, holding
_____________
RESET low. Resistor value (R1) is not critical. It should be about 100kΩ, large enough not to
_____________
_____________
load RESET and small enough to pull RESET to ground.
Monitoring Additional Supply Levels
It is possible to use the power-fail comparator to monitor a second supply as shown in Figure 9.
The two sensing resistors, R1 and R2, are selected such that the voltage on PFI drops below 1.25V
_________
________
at the minimum acceptable input supply. The P F O output can be connected to the M R input
so that a reset is generated when the supply drops out of tolerance. In this case, if either supply
drops out of tolerance, a reset is generated.
Monitoring a Negative Voltage
The power-fail comparator can also monitor a negative supply rail (Figure 10). When the negative
________
rail is good (a negative voltage of large magnitude), PFO is low, and when the negative rail is
________
degraded (a negative voltage of lesser magnitude), PFO is high. By adding the resistors and
________
________
transistor as shown, a high PFO triggers reset. As long as PFO remains high,
_____________
theUM706xS/UM708xS/UM813xS will keep reset asserted (RESET=low, RESET=high). Note
that this circuit’s accuracy depends on the PFI threshold tolerance, the VCC line, and the resistors.
Microprocessor with Bidirectional Reset
To prevent contention for microprocessors with a bidirectional reset line, a current limiting
_____________
resistor is to be inserted between the RESET output pin and the microprocessor reset pin. This
limits the current to a safe level if there are conflicting output reset levels. A suitable resistor
value is 4.7kΩ. If the reset output is required for other uses, it should be buffered as shown in
Figure 11.
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UM706xS/UM708xS/UM813xS
VX
+5V
VCC
VCC
RESET
To μP
R1
RESET
MR
R2
R1
PFI
GND
Figure 8. Reset Valid to Ground Circuit
GND
PFO
Figure 9. Monitoring an Additional Supply VX
+5V
100kΩ
VCC
MR
R1
100kΩ
PFI
PFO
RESET
GND
R2
2N3904
BUFFERED RESET TO OTHER SYSTEM COMPONENTS
To μP
VCC
VCC
V-
µP
+5V
MR
RESET
4.7kΩ
RESET
0V
+5V
PFO
0V
V5-1.25
R1
=
VTRIP
0V
GND
GND
1.25-VTRIP ,VTRIP<0
R2
Figure 10. Monitoring a Negative Voltage
Figure 11. Bidirectional Reset I/O
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UM706xS/UM708xS/UM813xS
Package Information
UM706xS SOP8
Outline Drawing
c
L
D
E
E1
Symbol
1
2
θ
e
Top View
A
A2
End View
A1
b
Side View
A
A1
A2
b
c
D
E
E1
e
L
θ
DIMENSIONS
MILLIMETERS
INCHES
Min
Max
Min
Max
1.350
1.750
0.053
0.069
0.100
0.250
0.004
0.010
1.350
1.550
0.053
0.061
0.33
0.51
0.013
0.020
0.170
0.250
0.006
0.010
4.700
5.100
0.185
0.200
3.800
4.000
0.150
0.157
5.800
6.200
0.228
0.244
1.270 (BSC)
0.050 (BSC)
0.400
1.270
0.016
0.050
0°
8°
0°
8°
4.95
1.30
Land Pattern
1.27
0.50
NOTES:
1. Compound dimension: 4.90×3.90;
2. Unit: mm;
3. General tolerance ±0.05mm unless otherwise
specified;
4. The layout is just for reference.
Tape and Reel Orientation
UM706
XS
XX
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UM706xS/UM708xS/UM813xS
UM708xS SOP8
Outline Drawing
c
L
D
E
E1
Symbol
1
2
θ
e
Top View
A
A2
End View
A1
b
Side View
A
A1
A2
b
c
D
E
E1
e
L
θ
DIMENSIONS
MILLIMETERS
INCHES
Min
Max
Min
Max
1.350
1.750
0.053
0.069
0.100
0.250
0.004
0.010
1.350
1.550
0.053
0.061
0.33
0.51
0.013
0.020
0.170
0.250
0.006
0.010
4.700
5.100
0.185
0.200
3.800
4.000
0.150
0.157
5.800
6.200
0.228
0.244
1.270 (BSC)
0.050 (BSC)
0.400
1.270
0.016
0.050
0°
8°
0°
8°
4.95
1.30
Land Pattern
1.27
0.50
NOTES:
1. Compound dimension: 4.90×3.90;
2. Unit: mm;
3. General tolerance ±0.05mm unless otherwise
specified;
4. The layout is just for reference.
Tape and Reel Orientation
UM708
XS
XX
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UM706xS/UM708xS/UM813xS
UM813xS SOP8
Outline Drawing
c
L
D
E
E1
Symbol
1
2
θ
e
Top View
A
A2
End View
A1
b
Side View
A
A1
A2
b
c
D
E
E1
e
L
θ
DIMENSIONS
MILLIMETERS
INCHES
Min
Max
Min
Max
1.350
1.750
0.053
0.069
0.100
0.250
0.004
0.010
1.350
1.550
0.053
0.061
0.33
0.51
0.013
0.020
0.170
0.250
0.006
0.010
4.700
5.100
0.185
0.200
3.800
4.000
0.150
0.157
5.800
6.200
0.228
0.244
1.270 (BSC)
0.050 (BSC)
0.400
1.270
0.016
0.050
0°
8°
0°
8°
4.95
1.30
Land Pattern
1.27
0.50
NOTES:
1. Compound dimension: 4.90×3.90;
2. Unit: mm;
3. General tolerance ±0.05mm unless otherwise
specified;
4. The layout is just for reference.
Tape and Reel Orientation
UM813
XS
XX
________________________________________________________________________
http://www.union-ic.com Rev.05 Mar.2015
16/17
UM706xS/UM708xS/UM813xS
IMPORTANT NOTICE
The information in this document has been carefully reviewed and is believed to be
accurate. Nonetheless, this document is subject to change without notice. Union assumes
no responsibility for any inaccuracies that may be contained in this document, and makes
no commitment to update or to keep current the contained information, or to notify a
person or organization of any update. Union reserves the right to make changes, at any
time, in order to improve reliability, function or design and to attempt to supply the best
product possible.
Union Semiconductor, Inc
Add: Unit 606, No.570 Shengxia Road, Shanghai 201210
Tel: 021-51093966
Fax: 021-51026018
Website: www.union-ic.com
________________________________________________________________________
http://www.union-ic.com Rev.05 Mar.2015
17/17