NSC LM3712YW4BP308 Microprocessor supervisory circuits with separate watchdog timer output, power fail input and manual reset Datasheet

LM3712/LM3713
Microprocessor Supervisory Circuits with Separate
Watchdog Timer Output, Power Fail Input and Manual
Reset
General Description
Features
The LM3712/LM3713 series of microprocessor supervisory
circuits provide the maximum flexibility for monitoring power
supplies and battery controlled functions in systems without
backup batteries. The LM3712/LM3713 series are available
in a 9-bump micro SMD package.
Built-in features include the following:
n Standard Reset Threshold voltage: 3.08V
n Custom Reset Threshold voltages: For other voltages
between 2.2V and 5.0V in 10mV increments, contact
National Semiconductor Corp.
n No external components required
n Manual-Reset input
n RESET (LM3712) or RESET (LM3713) outputs
n Precision supply voltage monitor
n Factory programmable Reset and Watchdog Timeout
Delays
n Separate Watchdog output
n Separate Power Fail comparator
n Available in micro SMD package for minimum footprint
n ± 0.5% Reset threshold accuracy at room temperature
n ± 2% Reset threshold accuracy over temperature
extremes
n Reset assertion down to 1V VCC (RESET option only)
n 28 µA VCC supply current
Reset: Reset is asserted during power-up, power-down, and
brownout conditions. RESET is guaranteed down to VCC of
1.0V.
Manual Reset Input: An input that asserts reset when pulled
low.
Power-Fail Input: A 1.225V threshold detector for power fail
warning, or to monitor a power supply other than VCC.
Watchdog Timer: The WDI (Watchdog Input) monitors one of
the µP’s output lines for activity. If no output transition occurs
during the watchdog timeout period, the watchdog output
(WDO) pulls low.
Applications
n
n
n
n
Embedded Controllers and Processors
Intelligent Instruments
Automotive Systems
Critical µP Power Monitoring
Typical Application
20011903
© 2002 National Semiconductor Corporation
DS200119
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LM3712/LM3713 Microprocessor Supervisory Circuits with Separate Watchdog Timer Output,
Power Fail Input and Manual Reset
July 2002
LM3712/LM3713
Connection Diagram
Top View
(looking from the coating side)
micro SMD 9 Bump Package
BPA09
20011901
Pin Description
Bump No.
Name
A1
MR
Manual-Reset input. When MR is less than VMRT (Manual Reset Threshold)
RESET/RESET is engaged.
Function
B1
VCC
Power Supply input.
C1
RESET
Reset Logic Output. Pulses low for tRP (Reset Timeout Period) when triggered, and stays
low whenever VCC is below the reset threshold or when MR is below VMRT. It remains low
for tRP after either VCC rises above the reset threshold, or after MR input rises above
VMRT (LM3712 only).
RESET
Reset Logic Output. RESET is the inverse of RESET (LM3713 only).
C2
PFO
Power-Fail Logic Output. When PFI is below VPFT PFO goes low; otherwise, PFO remains
high.
C3
WDO
Watchdog Output. If no digital activity is detected on WDI (Watchdog Input) for a period
exceeding tWD, this output pulls low.
B3
GND
Ground reference for all signals.
A3
WDI
Watchdog Input Transition Monitor: If no transition activity occurs for a period exceeding
tWD (Watchdog Timeout Period), reset is engaged.
A2
PFI
Power-Fail Comparator Input. When PFI is less than VPFT (Power-Fail Reset Threshold),
the PFO goes low; otherwise, PFO remains high.
B2
NC
No Connect. Test input used at factory only. Leave floating.
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2
LM3712/LM3713
Block Diagram
20011905
3
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LM3712/LM3713
Ordering Information
20011904
*For other voltages between 2.2V and 5.0V, please contact National Semiconductor sales office.
LM3712/LM3713
Part Number
Output
Reset Timeout
Period
Watchdog
Timeout Period
Package
Marking
LM3712XQBP-308
totem-pole
200ms
1600ms
%%IC
LM3712XQBPX-308
totem-pole
200ms
1600ms
%%IC
LM3713XQBP-308
totem-pole
200ms
1600ms
%%ID
LM3713XQBPX-308
totem-pole
200ms
1600ms
%%ID
%% is the datecode and will vary with time.
Table Of Functions
Part
Number
LM3712
LM3713
Active
Low
Reset
Active
High
Reset
x
x
Output
(X = totem-pole)
(Y = open-drain)
Reset
Timeout
Period
Watchdog
Timeout
Period
Manual
Reset
Power Fail
Comparator
X, Y*
Customized
Customized
x
x
X
Customized
Customized
x
x
* = available upon request. Contact National
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4
(Note 1)
Power Dissipation
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage (VCC)
Operating Ratings (Note 1)
−0.3V to 6.0V
All Other Inputs
(Note 3)
−40˚C ≤ TJ ≤ 85˚C
Temperature Range
−0.3V to VCC + 0.3V
ESD Ratings (Note 2)
Human Body Model
Machine Model
1.5kV
150V
LM3712/LM3713 Series Electrical Characteristics
Limits in the standard typeface are for TJ = 25˚C and limits in boldface type apply over full operating range. Unless otherwise
specified: VCC = +2.2V to 5.5V.
Symbol
Parameter
Conditions
Min
Typ
Max
Units
POWER SUPPLY
VCC
ICC
Operating Voltage
Range: VCC
LM3712
1.0
5.5
LM3713
1.2
5.5
VCC Supply
Current
All inputs = VCC; all outputs floating
V
28
50
µA
VRST
+0.5
+2
%
RESET THRESHOLD
VRST
Reset Threshold
VCC falling
−0.5
−2
VCC falling: TA = 0˚C to 70˚C
VRSTH
tRP
tRD
−1.5
+1.5
0.0032 • VRST
Reset Threshold
Hysteresis
Reset Timeout
Period
Reset
Reset
Reset
Reset
Timeout
Timeout
Timeout
Timeout
Period
Period
Period
Period
VCC to Reset
Delay
VCC falling at 1mV/µs
=
=
=
=
E, J, N, S
F, K, P, T
G, L, Q, U
H, M, R, V
1
20
140
1120
1.4
28
200
1600
mV
2
40
280
2240
20
ms
µs
RESET (LM3713)
VOL
RESET
VCC > 2.25V, ISINK = 900µA
VCC
VCC
VOH
RESET
VCC
VCC
VCC
VCC
VCC
ILKG
Output Leakage
Current
>
>
>
>
>
>
>
0.3
2.7V, ISINK = 1.2mA
0.3
4.5V, ISINK = 3.2mA
0.4
1.2V, ISOURCE = 50µA
0.8 VCC
1.8V, ISOURCE = 150µA
0.8 VCC
2.25V, ISOURCE = 300µA
0.8 VCC
2.7V, ISOURCE = 500µA
0.8 VCC
4.5V, ISOURCE = 800µA
VCC − 1.5V
V
V
VRESET = 5.5V
1.0
VCC > 1.0V, ISINK = 50µA
0.3
µA
RESET (LM3712)
VOL
RESET
VCC
VCC
VCC
VCC
VOH
RESET
VCC
VCC
VCC
>
>
>
>
>
>
>
1.2V, ISINK = 100µA
0.3
2.25V, ISINK = 900µA
0.3
2.7V, ISINK = 1.2mA
0.3
4.5V, ISINK = 3.2mA
0.4
2.25V, ISOURCE = 300µA
0.8 VCC
2.7V, ISOURCE = 500µA
0.8 VCC
4.5V, ISOURCE = 800µA
VCC − 1.5V
5
V
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LM3712/LM3713
Absolute Maximum Ratings
LM3712/LM3713
LM3712/LM3713 Series Electrical Characteristics
(Continued)
Limits in the standard typeface are for TJ = 25˚C and limits in boldface type apply over full operating range. Unless otherwise
specified: VCC = +2.2V to 5.5V.
Symbol
Parameter
Conditions
Min
Typ
Max
Units
+1
µA
WDI
WDI
Watchdog Input
Current
WDIT
Watchdog Input
Threshold
tWD
Watchdog
Timeout Period
−1
Watchdog
Watchdog
Watchdog
Watchdog
Timeout
Timeout
Timeout
Timeout
Period
Period
Period
Period
=
=
=
=
E, F, G, H
J, K, L, M
N, P, Q, R
S, T, U, V
0.2 • VCC
1.225
0.8 • VCC
V
4.3
71
1120
17900
6.2
102
1600
25600
9.3
153
2400
38400
ms
1.200
1.225
1.250
V
PFI/MR
VPFT
PFI Input
Threshold
VMRT
MR Input
Threshold
MR, Low
0.8
MR, High
PFI/MR falling: VCC = VRST
2.0
0.0032 • VRST
VPFTH/
VMRTH
PFI/MR Threshold
Hysteresis
IPFI
Input Current (PFI
only)
−75
RMR
MR Pull-up
Resistance
35
tMD
MR to Reset
Delay
tMR
MR Pulse Width
MAX
to 5.5V
56
V
mV
75
nA
75
kΩ
12
µS
25
µS
PFO, WDO
VOL
PFO, WDO
Output Voltage
VCC > 2.25V, ISINK = 900µA
0.3
VCC > 2.7V, ISINK = 1.2mA
0.3
VCC > 4.5V, ISINK = 3.2mA
0.4
VCC > 2.25V, ISOURCE = 300µA
VOH
0.8 VCC
VCC > 2.7V, ISOURCE = 500µA
0.8 VCC
VCC > 4.5V, ISOURCE = 800µA
VCC − 1.5V
V
LLO OUTPUT
VLLOT
LLO Output
Threshold
(VLLO − VRST, VCC
falling)
VLLOTH
Low-Line
Comparator
Hysteresis
tCD
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Low-Line
Comparator Delay
1.01 • VRST
VCC falling at 1mV/µs
6
1.02 • VRST
1.03 • VRST
V
0.0032 • VRST
mV
20
µs
(Continued)
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device
is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the
listed conditions.
Note 2: The Human Body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200pF capacitor discharged
directly into each pin.
Note 3: The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(MAX), the junction-to-ambient thermal resistance, θJ-A,
and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperture is calculated using:
Where the value of θJ-A for the micro SMD package is 220˚C/W.
7
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LM3712/LM3713
LM3712/LM3713 Series Electrical Characteristics
LM3712/LM3713
Typical Performance Characteristics
Supply Current vs Supply Voltage
3.3V Supply Current vs Temperature
20011911
20011915
Normalized Reset Threshold Voltage vs Temperature
Reset Timeout Period vs VCC
20011912
20011932
Max. Transient Duration vs Reset Comparator Overdrive
(VCC = 3.3V)
Reset Timeout Period vs Temperature
20011910
20011916
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8
LM3712/LM3713
Typical Performance Characteristics
(Continued)
Watchdog Timeout Period vs Temperature
(tWD programmed as 6.2ms)
20011913
9
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LM3712/LM3713
the voltage at PFI drops below VPFT several milliseconds
before the main supply voltage drops below the reset threshold, providing advanced warning of a brownout.
The voltage threshold is set by R1 and R2 and is calculated
as follows:
Circuit Information
Reset Output
The Reset input of a µP initializes the device into a known
state. The LM3712/LM3713 microprocessor supervisory circuits assert a forced reset output to prevent code execution
errors during power-up, power-down, and brownout conditions.
RESET is guaranteed valid for VCC > 1V. Once VCC exceeds the reset threshold, an internal timer maintains the
output for the reset timeout period. After this interval, reset
goes high. The LM3712 offers an active-low RESET; The
LM3713 offers an active-high RESET.
Note this comparator is completely separate from the rest of
the circuitry, and may be employed for other functions as
needed.
Watchdog Timer Input (WDI)
The watchdog timer input monitors one of the microprocessor’s output lines for activity. Each time a transition occurs on
this monitored line, the watchdog counter is reset. However,
if no transition occurs and the timeout period is reached, the
LM3712/LM3713 assumes that the microprocessor has
locked up and the watchdog output WDO, is activated.
WDI is a high impedance input. WDO is an active-low totem
pole output.
Any time VCC drops below the reset threshold (such as
during a brownout), the reset activates. When VCC again
rises above the reset threshold, the internal timer starts.
Reset holds until VCC exceeds the reset threshold for longer
than the reset timeout period. After this time, reset releases.
The Manual Reset input (MR) will initiate a forced reset also.
See the Manual Reset Input section.
Reset Threshold
The LM3712/LM3713 family is available with a reset voltage
of 3.08V. Other reset thresholds in the 2.20V to 5.0V range,
in steps of 10 mV, are available; contact National Semiconductor for details.
Special Precautions for the micro SMD Package
As with most integrated circuits, the LM3712 and LM3713
are sensitive to exposure from visible and infrared (IR) light
radiation. Unlike a plastic encapsulated IC, the micro SMD
package has very limited shielding from light, and some
sensitivity to light reflected from the surface of the PC board
or long wavelength IR entering the die from the side may be
experienced. This light could have an unpredictable affect on
the electrical performance of the IC. Care should be taken to
shield the device from direct exposure to bright visible or IR
light during operation.
Manual Reset Input (MR)
Many µP-based products require a manual reset capability,
allowing the operator to initiate a reset. The MR input is fully
debounced and provides an internal 56 kΩ pull-up. When the
MR input is pulled below VMRT (1.225V) for more than 25 µs,
reset is asserted after a typical delay of 12 µs. Reset remains
active as long as MR is held low, and releases after the reset
timeout period expires after MR rises above VMRT. Use MR
with digital logic to assert or to daisy chain supervisory
circuits. It may be used as another low-line comparator by
adding a buffer.
Micro SMD Mounting
The micro SMD package requires specific mounting techniques which are detailed in National Semiconductor Application Note AN-1112. Referring to the section Surface
Mount Technology (SMT) Assembly Considerations, it
should be noted that the pad style which must be used with
the 9-pin package is the NSMD (non-solder mask defined)
type.
For best results during assembly, alignment ordinals on the
PC board may be used to facilitate placement of the micro
SMD device.
Power-Fail Comparator (PFI/PFO)
The PFI is compared to a 1.225V internal reference, VPFT. If
PFI is less than VPFT, the Power Fail Output PFO drops low.
The power-fail comparator signals a falling power supply,
and is driven typically by an external voltage divider that
senses either the unregulated supply or another system
supply voltage. The voltage divider generally is chosen so
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10
LM3712/LM3713
Timing Diagrams
20011928
FIGURE 1. LM3712 Reset Time with MR
20011930
FIGURE 2. PFI Comparator Timing Diagram
11
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LM3712/LM3713
Typical Application Circuits
20011918
FIGURE 3. Monitoring Two Critical Supplies Plus Dataline
20011919
FIGURE 4. Monitoring Two Supplies plus Manual Reset And Dataline
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12
inches (millimeters)
NOTES: UNLESS OTHERWISE SPECIFIED
1. EPOXY COATING
2. 63Sn/37Pb EUTECTIC BUMP
3. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD.
4. PIN 1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION. REMAINING PINS ARE NUMBERED COUNTER
CLOCKWISE.
5. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS
PACKAGE HEIGHT.
6.NO JEDEC REGISTRATION AS OF AUG.1999.
9 bump micro SMD Package
NS Package Number BPA09FFB
The dimensions of X1, X2 and X3 are given below
X1 = 1.412mm
X2 = 1.412mm
X3 = 0.850mm
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LM3712/LM3713 Microprocessor Supervisory Circuits with Separate Watchdog Timer Output,
Power Fail Input and Manual Reset
Physical Dimensions
unless otherwise noted
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