lm9073 National Semiconductor Corporation, lm9073 Datasheet - Page 9

• Manufacturer Part Number: lm9073
• Description: Dual High Current Low-dropout System Regulator
• Manufacturer: National Semiconductor Corporation

Application Information
current on either output the regulator requires 15mA maxi-
mum quiescent current for biasing internal circuitry. During
dropout conditions (V
can rise to 50% of the total load current. With less than 3V
applied to the input, internal biasing circuitry shuts OFF.
When switched OFF the regulator can remain connected to
the battery supply with a current drain of less than 100µA.
MAIN OUTPUT (PIN 10)
The Main Output regulator provides a well controlled (2%
tolerance maximum) 5V supply line with a total load current
ranging up to 700mA. This relatively high level of output
current is sufficient to provide power to a large number of
load circuits in a variety of module applications.
This output has a short to ground current limit between
900mA and 2A. It is not protected for shorts to battery
however, but can withstand an output short to a potential of
7 Volts or less.
To maintain stability of this supply line an output bypass
capacitor is required. This capacitor must be at least 6µF
with an equivalent series resistance (ESR) between 0.3Ω
and 3Ω over temperature.
RESET OUTPUT (PIN 7)
The Reset Output is an active low logic signal provided to
reset a system mircocontroller on power up and in the event
that the Main Output falls out of regulation. This output is
guaranteed to provide a logic low level (
the Main Output supply is below a threshold set by the Reset
Adjust pin strap option (see Reset Adjust section) or is pulled
IN
<
5.5V) the additional input current
FIGURE 2. Reset Generator and Watchdog Circuitry
<
(Continued)
0.4V) whenever
9
The Main Output is sensed for the generation of the system
reset output.
EXTERNAL SUPPLY OUTPUT (PIN 5)
The External Supply Output regulator is a secondary 5V, 2%
tolerance regulated output of the LM9073. this 100mA output
is available to bias sensors and other devices located exter-
nal to the main system module.
For providing remote power the External Supply Output is
fully protected against short circuit connections to the battery
or input supply (up to 27V) and to ground. These shorted
fault conditions do not effect the operation of the main supply
nor generate a reset of the system.
Like the main output a bypass capacitor is required for
stability. This capacitor should be also greater than 6µF with
an ESR between 0.3Ω and 3Ω.
above 5.75V. This general reset prevents erratic system
operation which may occur with out-of-specification supply
potentials.
The Reset Output has an active pull down which can sink up
to 15mA of current and a passive pull-up (through a 4KΩ
resistor) to the Main Output to ensure voltage compatibility
with the system supply. Capacitive loading on this reset line
will directly affect the rise time of the reset signal. The Reset
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