NSC LM3704XDBPX-308 Microprocessor supervisory circuits with power fail input, low line output and manual reset Datasheet

LM3704/LM3705
Microprocessor Supervisory Circuits with Power Fail
Input, Low Line Output and Manual Reset
General Description
The LM3704/LM3705 series of microprocessor supervisory
circuits provide the maximum flexibility for monitoring power
supplies and battery controlled functions in systems without
backup batteries. The LM3704/LM3705 series are available
in MSOP-10 and 9-bump micro SMD packages.
Built-in features include the following:
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.
Low Line Output: This early power failure warning indicator
goes low when the supply voltage drops to a value which is
2% higher than the reset threshold voltage.
No external components required
Manual-Reset input
RESET (LM3704) or RESET (LM3705) outputs
Precision supply voltage monitor
Factory programmable Reset Timeout Delay
Separate Power Fail comparator
Available in micro SMD package for minimum footprint
± 0.5% Reset threshold accuracy at room temperature
± 2% Reset threshold accuracy over temperature
extremes
n Reset assertion down to 1V VCC (RESET option only)
n 28 µA VCC supply current
n
n
n
n
n
n
n
n
n
Applications
n
n
n
n
Embedded Controllers and Processors
Intelligent Instruments
Automotive Systems
Critical µP Power Monitoring
Features
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.
Typical Application
10136903
© 2002 National Semiconductor Corporation
DS101369
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LM3704/LM3705 Microprocessor Supervisory Circuits with Power Fail Input, Low Line Output and
Manual Reset
July 2002
LM3704/LM3705
Connection Diagram
Top View
(looking from the coating side)
micro SMD 9 Bump Package
BPA09
MSOP-10
10136902
10136901
Pin Description
Pin No.
Name
Function
micro
SMD
MSOP
A1
2
MR
Manual-Reset input. When MR is less than VMRT (Manual Reset Threshold)
RESET/RESET is engaged.
B1
1
VCC
Power Supply input.
C1
10
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 (LM3704 only).
RESET
Reset Logic Output. RESET is the inverse of RESET (LM3705 only).
C2
8
PFO
Power-Fail Logic Output. When PFI is below VPFT, PFO goes low; otherwise, PFO
remains high.
C3
7
LLO
Low-Line Logic Output. Early Power-Fail warning output. Low when VCC falls below VLLOT
(Low-Line Output Threshold). This output can be used to generate an NMI (Non-Maskable
Interrupt) to provide an early warning of imminent power-failure.
B3
5
GND
Ground reference for all signals.
A3
4, 6
NC
No Connect.
A2
3
PFI
Power-Fail Comparator Input. When PFI is less than VPFT (Power-Fail Reset Threshold),
the PFO goes low; otherwise, PFO remains high.
B2
9
NC
No Connect. Test input used at factory only. Leave floating.
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2
LM3704/LM3705
Block Diagram
10136926
3
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LM3704/LM3705
Ordering Information
10136904
*For other voltages between 2.2V and 5.0V, please contact National Semiconductor sales office.
LM3704/LM3705
Package
Part Number
Output
Reset Timeout
Period
LM3704XCBP-308
totem-pole
200ms
x
%%I4
LM3704XCBPX-308
totem-pole
200ms
x
%%I4
LM3704XCMM-308
totem-pole
200ms
x
LM3704XCMMX-308
totem-pole
200ms
x
LM3705XCBP-308
totem-pole
200ms
x
%%I5
LM3705XCBPX-308
totem-pole
200ms
x
%%I5
LM3705XCMM-308
totem-pole
200ms
x
R36B
LM3705XCMMX-308
totem-pole
200ms
x
R36B
MSOP
micro
SMD
Package
Marking
R35B
R35B
%% is the datecode and will vary with time.
Table Of Functions
Part
Number
LM3704
LM3705
Active
Low
Reset
Active
High
Reset
x
x
Output
(X = totem-pole)
(Y = open-drain)
Reset
Timeout
Period
Power Fail
Comparator
Low
Line
Output
X, Y*
Customized
x
x
x
X
Customized
x
x
x
* = available upon request. Contact National
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Manual
Reset
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
LM3704/LM3705 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
LM3704
1.0
5.5
LM3705
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
=
=
=
=
A
B
C
D
1
20
140
1120
1.4
28
200
1600
mV
2
40
280
2240
20
ms
µs
RESET (LM3705)
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 (LM3704)
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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LM3704/LM3705
Absolute Maximum Ratings
LM3704/LM3705
LM3704/LM3705 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
1.200
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, LLO
VOL
PFO, LLO Output
Voltage
VOH
VCC > 2.25V, ISINK = 900µA
0.3
VCC > 2.7V, ISINK = 1.2mA
0.3
VCC > 4.5V, ISINK = 3.2mA
0.4
VCC
VCC
VCC
> 2.25V, ISOURCE = 300µA
> 2.7V, ISOURCE = 500µA
> 4.5V, ISOURCE = 800µA
0.8 VCC
V
0.8 VCC
VCC − 1.5V
LLO OUTPUT
VLLOT
LLO Output
Threshold
(VLLO − VRST, VCC
falling)
VLLOTH
Low-Line
Comparator
Hysteresis
tCD
Low-Line
Comparator Delay
1.01 • VRST
VCC falling at 1mV/µs
1.02 • VRST
1.03 • VRST
V
0.0032 • VRST
mV
20
µs
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 MSOP-10 package is 195˚C/W in a typical PC board mounting and the micro SMD package is 220˚C/W.
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6
Supply Current vs Supply Voltage
3.3V Supply Current vs Temperature
10136911
10136915
Normalized Reset Threshold Voltage vs Temperature
Reset Timeout Period vs VCC
10136912
10136932
Max. Transient Duration vs Reset Comparator Overdrive
(VCC = 3.3V)
Reset Timeout Period vs Temperature
10136910
10136916
7
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LM3704/LM3705
Typical Performance Characteristics
LM3704/LM3705
Typical Performance Characteristics
(Continued)
Low-Line Comparator Propagation Delay vs Temperature
10136914
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8
Reset Output
The Reset input of a µP initializes the device into a known
state. The LM3704/LM3705 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 LM3704 offers an active-low RESET; The
LM3705 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.
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.
Low-Line Output (LLO)
The low-line output comparator is typically used to provide a
non-maskable interrupt to a µP when VCC begins falling. LLO
monitors VCC and goes low when VCC falls below VLLOT
(typically 1.02 • VRST) with hysteresis of 0.0032 • VRST.
The Manual Reset input (MR) will initiate a forced reset also.
See the Manual Reset Input section.
Special Precautions for the micro SMD Package
Reset Threshold
As with most integrated circuits, the LM3704 and LM3705
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.
The LM3704/LM3705 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.
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
9
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LM3704/LM3705
supply voltage. The voltage divider generally is chosen so
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
LM3704/LM3705
Timing Diagrams
10136928
FIGURE 1. LM3704 Reset Time with MR
10136929
FIGURE 2. LLO Output
10136930
FIGURE 3. PFI Comparator Timing Diagram
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LM3704/LM3705
Typical Application Circuits
10136918
FIGURE 4. Monitoring Two Critical Supplies
10136919
FIGURE 5. Monitoring Two Supplies plus Manual Reset
11
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LM3704/LM3705
Typical Application Circuits
(Continued)
10136920
FIGURE 6. Monitoring Dual Supplies plus External Fault Input
10136921
Note: MR input with its 1.225V nominal threshold, may monitor an additional supply voltage. An internal 56 kΩ pull-up resistor is
included on this input.
FIGURE 7. Microprocessor Supervisor with Early Warning Detector
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LM3704/LM3705
Typical Application Circuits
(Continued)
10136924
FIGURE 8. LM3705 Power-On Delay
13
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LM3704/LM3705
Typical Application Circuits
(Continued)
10136923
FIGURE 9. LM3705 Power-On Delay with Overvoltage Protection
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14
LM3704/LM3705
Typical Application Circuits
(Continued)
10136922
FIGURE 10. Regulator/Switch with Long-Term Overvoltage Lockout Prevents Overdissipation in Linear Regulator
10136931
FIGURE 11. Switch Debouncer
15
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LM3704/LM3705
Physical Dimensions
inches (millimeters)
unless otherwise noted
10 Lead MSOP Package
NS Package Number MUB10A
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16
inches (millimeters) unless otherwise noted (Continued)
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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COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
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whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
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LM3704/LM3705 Microprocessor Supervisory Circuits with Power Fail Input, Low Line Output and
Manual Reset
Physical Dimensions
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