Control Logic Truth Table

ON/OFF Input Keep-Alive Input Main Output Voltage External Supply Output

Voltage

Reset Output

Operating Condition

L

L

0V

0V

0V

Rising Edge

L

5V

5V

Rising after delay

Outputs turn ON, Power ON

delayed reset

H

X

5V

5V

5V

Normal ON condition

HX

X0V

Main output pulled out of

regulation,

Reset flag generated.

Threshold depends on Reset

Adjust seting (pin 11)

Falling Edge

H

5V

5V

5V

Keep-Alive, Continued normal

operation

L

Rising Edge

5V

5V

Rising after delay

Outputs turned ON by

Keep-Alive Input

Application Information

Pin Description and Functionality

The LM9073 is a precision dual voltage regulator optimized

for use in powertrain module applications but will also find

use in a wide variety of automotive and industrial applica-

tions were precision supply regulation is required in harsh

operating environments. The following will describe the func-

tionality of each of the package pins.

Input Voltage (pin 4)

The LM9073 has been designed to connect directly to the ig-

nition or battery supply in automotive applications. For this

type of supply the regulator been designed to withstand up to

+60V and −45V supply transients such as load dump. An ov-

ervoltage shut down protection circuit turns OFF both of the

regulator outputs should supply transients exceed typically

+33V to fully protect all load circuitry. This higher threshold

allows normal operation with 24V

the event when two batteries are used to start a vehicle. Pro-

tection of the system is also provided for inadvertent reverse

polarity battery connections.

The current drain on the supply line is directly proportional to

the load currents on the two voltage regulators. With no load

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% tol-

erance maximum) 5V supply line with a total load current

Figure 1. Circuit Block Diagram

DS101296-16

www.national.com

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