LM9074
LM9074 System Voltage Regulator with Keep-Alive ON/OFF Control
Literature Number: SNVS078E
LM9074
System Voltage Regulator with Keep-Alive ON/OFF
Control
General Description
The LM9074 is a 5V, 3% accurate, 180 mA NPN voltage
regulator. The regulator features an active low delayed reset
output flag which can be used to reset a microprocessor
system on turn-ON and in the event that the regulator output
falls out of regulation for any reason. An external capacitor
programs a delay time interval before the reset output can
return high.
Designed for automotive application the LM9074 contains a
variety of protection features such as reverse battery, overvoltage shutdown, thermal shutdown, input transient protection and a wide operating temperature range.
A unique two-input logic control scheme is used to enable or
disable the regulator output. An ON/OFF input can be provided by an ignition switch derived signal while a second,
Keep-Alive input, is generated by a system controller. This
allows for a system to remain ON after ignition has been
switched OFF. The system controller can then execute a
power-down routine and after which command the regulator
OFF to a low quiescent current state (60 µA max).
Design techniques have been employed to allow the regulator to remain operational and not generate false reset
signals when subjected to high levels of RF energy (300V/m
from 2 MHz to 400 MHz).
Features
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Automotive application reliability
3% output voltage tolerance
Insensitive to radiated RFI
Dropout voltage less than 2.5V with 180mA output
current
Externally programmed reset delay interval
Keep-alive feature with 2 logic control inputs
+40V Load dump transient protection
Thermal shutdown
Short circuit protection and disable safety features
Reverse battery protection
Low OFF quiescent current, 60µA maximum
Wide operating temperature range −40˚C to +125˚C
Connection Diagram and Ordering Information
(Top View)
14-Pin SO Package
10130502
Order Number LM9074M
See NS Package Number M14A
© 2005 National Semiconductor Corporation
DS101305
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LM9074 System Voltage Regulator with Keep-Alive ON/OFF Control
November 2005
LM9074
Absolute Maximum Ratings (Note 1)
Lead Temperature
(Soldering, 10 seconds)
Input Voltage
260˚C
Storage Temperature
ON/OFF, Keep-Alive Inputs
(through 1 kΩ)
DC Input Voltage
Operating Ratings (Note 1)
−26V to +26V
Positive Input Transient (t < 100 ms)
Negative Input Transient (t < 1 ms)
40V
Input Voltage
7.5V to 16.5V
−50V
Ambient Temperature
5 mA
θja, M14A Package
88˚C/W
Internally Limited
θjc, M14A Package
34˚C/W
Reset Output Sink Current
Power Dissipation
−50˚C to +150˚C
Junction Temperature
−40˚C to +125˚C
150˚C
ESD Susceptibility (Note 2)
12 kV, 2 kV
Electrical Characteristics
The following specifications apply for VCC= 7.5V to 16.5V, −40˚C ≤ TA≤ 125˚C, unless otherwise specified. COUT=0.1µF.
Symbol
Parameter
Conditions
Min
Max
4.85
Units
REGULATOR OUTPUT
VOUT
Output Voltage
20 mA ≤ IOUT ≤ 180 mA
5.15
V
∆VOUT Line
Line Regulation
IOUT = 20 mA, 9V ≤ VIN ≤ 16.5V
IOUT = 20 mA, 7.5V ≤ VIN ≤ 16.5V
25
50
mV
mV
∆VOUT Load
Load Regulation
VIN = 14.4V, 20 mA ≤ IOUT ≤ 180 mA
50
mV
Iq
Quiescent Current
4V ≤ VON/OFF ≤ VIN
20mA ≤ IOUT ≤ 180mA
25
mA
Ioff
OFF Quiescent Current
VIN ≤ 16.5V, Regulator OFF
−40˚C ≤ TJ ≤ 60˚C
60˚C ≤ TJ ≤ 135˚C
20
60
µA
µA
2.0
2.5
V
V
1.0
A
Vdo
Dropout Voltage
IOUT = 20 mA
IOUT = 180 mA
Isc
Short Circuit Current
RL = 1Ω
0.4
PSRR
Ripple Rejection
VIN = (14VDC) + (1VRMS
VothOFF
Safety VOUT Latch-OFF Threshold
In Keep-Alive mode
@ 120Hz)
IOUT = 50 mA
VON/OFF = 0V, VKA = 0V
Vo Transient
60
4.5
V
5.5
V
−500
mV
Isink = 1.6 mA, VOUT > 3.2V
0.4
V
1.4V ≤ VOUT ≤ 3.2V
0.8
V
VOUT during Transients
VIN Peak ≤ 40V,
RL = 100Ω, τ = 100 ms
Threshold Voltage
∆VOUT Required to Generate a Reset
Output
4.85V ≤ VOUT ≤ 5.15V
4
dB
RESET OUTPUT
Vth
Vlow
Reset Output Low Voltage
Vhigh
Reset Output High Voltage
tdelay
Delay Time
Idelay
Rpu
−300
0.9 VOUT
VOUT
V
7
45
ms
Charging Current for Cdelay
−7
25
µA
Internal Pull-up Resistance
12
80
kΩ
Cdelay = 0.1 µFd
CONTROL LOGIC
VKAlow
Low Input Threshold Voltage,
Keep-Alive Input
3.5V ≤ VOUT ≤ 5.25V
0.3 VOUT
0.5 VOUT
V
VKAhigh
High Input Threshold Voltage,
Keep-Alive Input
3.5V ≤ VOUT ≤ 5.25V
0.6 VOUT
0.8 VOUT
V
VON/OFF low
Low Input Voltage, ON/OFF Input
Rseries = 1 kΩ
−2
2
V
VON/OFF high
High Input Voltage, ON/OFF Input
Rseries = 1 kΩ
4
VIN
V
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2
LM9074
Electrical Characteristics
(Continued)
The following specifications apply for VCC= 7.5V to 16.5V, −40˚C ≤ TA≤ 125˚C, unless otherwise specified. COUT=0.1µF.
Symbol
Parameter
Conditions
Min
Max
Units
VON/OFF ≤ 4V
330
µA
4V < VON/OFF < 7V
670
µA
VON/OFF ≥ 7V
10
mA
CONTROL LOGIC
ION/OFF
Input Current, ON/OFF Input
RpuKA
Internal Pull-up Resistance,
Keep-Alive Input
20
100
kΩ
RpdON/OFF
Internal Pull-down Resistance
ON/OFF Input
50
210
kΩ
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 conditions, see the Electrical Characteristics.
Note 2: All pins will survive an ESD impulse of ± 2000V using the human body model of 100 pF discharged through a 1.5 kΩ resistor. In addition, input pins VIN and
the ON/OFF input will withstand ten pulses of ± 12 kV from a 150 pF capacitor discharged through a 560Ω resistor with each pin bypassed with a 22 nF, 100V
capacitor.
Reset Operation and Protection Features
10130505
3
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LM9074
Typical Performance Characteristics
(TA = 25˚C unless indicated otherwise)
Turn ON Characteristics
Turn OFF Characteristics
10130506
10130507
Reset Delay Time
vs Temperature
10130513
ON/OFF, Keep-Alive and Safety
Latch-Off Control Diagrams
Keep-Alive Mode; Turn ON with ON/OFF control,
Keep output biased with Keep-Alive input,
Turn OFF with Keep-Alive (Keep-Alive low keeps
output ON, Keep-Alive going high turns output OFF)
Note: If Keep-Alive is provided by a microprocessor powered by the output
voltage of the LM9074, the logic “1” voltage level will track VOUT as the
regulator turns OFF.
Simple ON/OFF control
(Keep-Alive input must be high to turn OFF output)
10130519
10130518
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4
Safety Latch OFF of VOUT when in Keep-Alive Mode
(ON/OFF going high required to turn Output back ON)
(Continued)
Switch ON with ON/OFF input; Keep output
biased with Keep-Alive; Hold ouput ON with
ON/OFF; Turn OFF with ON/OFF input.
(Temporary Keep-Alive Mode)
10130521
10130520
Control Logic Truth Table
ON/OFF
Input
Keep-Alive
Input
Output
Voltage
Reset
Output
Operating Condition
L
X
0V
L
↑
X
5V
↑ after delay
Low quiescent current standby (OFF) condition
H
X
5V
H
Normal ON condition
↓
H
0V
L
Output turns OFF
↓
L
5V
H
Output kept ON by Keep-Alive Input
↑
L
5V
H
Output remains ON (or turns ON)
H
X
∆VOUT ≥ −300 mV
L
Output pulled out of regulation, reset flag generated
L
L
VOUT ≤ 4V
L
Output latches OFF
5
Output turns ON
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LM9074
ON/OFF, Keep-Alive and Safety
Latch-Off Control Diagrams
LM9074
Block Diagram
10130522
immunity to RFI the output bypass capacitor is important
(47 µF is recommended).
This regulator is suitable for applications where continuous
connection to the battery is required (Refer to the Typical
Application Circuit ). ON/OFF control of the regulator and
system can be accomplished by switching the ON/OFF input
to the battery or ignition supply VIN supply through a SPST
switch. If this input becomes open circuited, an internal
pull-down resistor ensures that the regulator turns OFF.
When the regulator is switched OFF the current load on the
battery drops to less than 60 µA. With the possibility in many
applications for VIN and the ON/OFF input pins to be connected in a system through long lengths of wire, the ESD
protection of these pins has been increased to 12 kV with the
addition of small input bypass capacitors.
Application Information
The LM9074 voltage regulator has been optimized for use in
microprocessor based automotive systems. Several unique
design features have been incorporated to address many
FMEA (Failure Mode Effects Analysis) concerns for fail-safe
system performance.
FAULT TOLERANT FEATURES
While not specifically guaranteed due to production testing
limitations, the LM9074 has been tested and shown to continue to provide a regulated output and, not generate an
erroneous system reset signal while subjected to high levels
of RF electric field energy (up to 300 V/m signal strength
over a 2 MHz to 400 MHz frequency range). This is very
important in vehicle safety related applications where the
system must continue to operate normally. To maintain this
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6
LM9074
Application Information
(Continued)
10130523
FIGURE 1. Typical Application Circuit
An output bypass capacitor of at least 0.1µF is required for
stability (47 µF is recommended). An input capacitor of 1 µF
or larger is recommended to improve line transient and noise
performance.
of the regulator. When the regulator is switched ON, conventional current limiting and thermal shutdown protect the regulator. When the regulator is switched OFF however, a
grounded VCC supply to the micro (due to the shorted regulator output) will force the Keep-Alive input to be low and
thus try to maintain the Keep-Alive mode of operation. With
a shorted load, the drain on the battery could be as high as
1.5A. A separate internal circuit monitors the output voltage
of the regulator. If VOUT is less than 4V, as would be the case
with a shorted load, the Keep-Alive function is logically disabled to ensure that the regulator turns OFF and reverts to
less than a 60 µA load on the battery.
With the Keep-Alive input, a system microprocessor has the
ability to keep the regulator ON (with a logic “0” on KeepAlive) after the ON/OFF input has been commanded OFF. A
power-down sequence, when system variables are typically
stored in programmable memory, can be executed and take
as much time as necessary. At the end of the operation the
micro then pulls Keep-Alive high and the regulator and system turn OFF and revert to the low quiescent current standby
mode.
For additional system reliability, consideration has been
made for the possibility of a short circuited load at the output
10130524
FIGURE 2. Control Logic Not Used
Conventional load dump protection is built in to withstand up
to +60V and −50V transients. A 1 kΩ resistor in series with
the ON/OFF and Keep-Alive inputs are recommended to
provide the same level of transient protection for these pins
if required. Protection against reverse polarity battery connections is also built in. With a reversed battery the output of
the LM9074 will not go more negative than one diode drop
below ground. This will prevent damage to any of the 5V load
circuits.
For applications where the control logic is not required the
logic pins should be configured as shown in Figure 2. A
separate device, called the LM9071, can be used. The
LM9071 is available in a 5-lead TO-220 package and does
not provide control logic functions, but still retains all of the
protection features of the LM9074.
RESET FLAG
Excessive loading of the output to the point where the output
voltage drops by 300 mV to 500 mV will signal a reset flag to
the micro. This will warn of a VCC supply that may produce
unpredictable operation of the system. On power-up and
recovery from a fault condition the delay capacitor is used to
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LM9074
Application Information
tDELAY = ((3.4V x CDELAY) / IDELAY))
For a CDELAY value of 0.1 µF and a typical IDELAY of 12 µA,
the typical delay time will be:
tDELAY = ((3.4V x 0.1 µF) / 12 µA)) = 28.3 ms
(Continued)
hold the micro in a reset condition for a programmable time
interval to allow the system operating voltages and clock to
stabilize before executing code.
The typical delay time interval can be estimated using the
following equation:
10130526
MICROPROCESSOR SYSTEM REGULATOR WITH
KEEP-ALIVE INTERVAL AT TURN-OFF
The following circuit illustrates a system application utilizing
both of the logic control inputs of the LM9074. Closing the
ON/OFF switch powers ON the system. Once powered, the
system controller sets the Keep-Alive line low. The NPN
transistor is used only to signal the controller that the ON/
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OFF switch has been opened and the system is to be turned
OFF. Upon detecting this high level at the ON/OFF Sense
input line, the controller can then perform a power down
routine. The system will remain fully powered until the controller commands total shut down by taking the Keep-Alive
line high. The system then shuts OFF and reverts to a very
low current drain standby condition until switched back on.
8
LM9074
Application Information
(Continued)
10130525
9
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LM9074 System Voltage Regulator with Keep-Alive ON/OFF Control
Physical Dimensions
inches (millimeters) unless otherwise noted
14-Lead (0.150" Wide) Molded SO Package
Order Number LM9074M
NS Package Number M14A
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
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