Output Voltage vs Junction Temperature

20083038

Application Information

REGULATOR BASICS

This regulator is suitable for Automotive applications where

continuous connection to the battery is required (refer to the

Typical Application circuit).

The pass transistor of the regulator is an PNP device. A 10uF

capacitor on the V

in most circumstances. There is no maximum value for the

regulator output bypass capacitance.

INPUT CAPACITOR

The LM9076 requires a low source impedance to maintain

regulator stability because portions of the internal bias cir-

cuitry are connected directly to V

ceramic capacitor should be placed between the LM9076

V

OUTPUT CAPACITOR

An output capacitor is also required for stability. This capaci-

tor must be placed between the LM9076 V

pins, as close as is physically possible, using traces that are

not part of the main load current path.

The output capacitor must meet the requirements for mini-

mum capacitance and also maintain the appropriate ESR

value of the full operating ambient temperature range to

assure stability. There is no maximum limit for the output

capacitance value, as long as ESR is maintained. See the

Typical Performance Characteristics curves for details.

Solid tantalum capacitors are recommended as they gener-

ally maintain capacitance and ESR ratings over a wide tem-

perature range.

Ceramic capacitor types XR7 and X5R may be used if a

series resistor is added to simulate the ESR requirement.

Aluminum electrolytic capacitors are not recommend, as

they are subject to wide changes in capacitance and ESR

values across temperature.

DELAY CAPACITOR

The capacitor on the Delay pin must be a low leakage type

since the charge current is minimal (500nA typical) and the

pin must fully charge to 5V. Ceramic, Mylar, and polystyrene

capacitor types are generally recommended, although

changes in capacitance values across temperature changes

will have some effect on the delay timing.

SHUTDOWN PIN

The basic On/Off control of the regulator is accomplished

with the SHUTDOWN pin. By pulling the SHUTDOWN pin

high the regulator output is switched Off. When the regulator

is switched Off the load on the battery will be primarily due to

the SHUTDOWN pin current.

When the SHUTDOWN pin is low, or left open, the regulator

is switched On. When an unregulated supply, such as V

BATTERY , is used to pull the SHUTDOWN pin high a series

resistor in the range of 10K

Ω to 50KΩ is recommended to

provide reverse voltage transient protection of the SHUT-

DOWN pin. Adding a small capacitor (0.001uF typical) from

the SHUTDOWN pin to Ground will add noise immunity to

prevent accidental turn on due to noise on the supply line.

RESET FLAG

Proper operation of the RESET circuity is not guaranteed for

V

information on the status of the regulator V

Any condition that causes the V

cally 89% normal would cause the RESET pin to go low. This

will warn of a system Vcc supply that may cause abnormal

operation.

Of course, when the regulator is switched Off in normal

operation the RESET pin will be low.

If the regulator is On, and then switched off, the RESET flag

will go low when the V

capacitor has decayed adequately.

Excessive thermal dissipation of the device such that the

Thermal Shutdown circuit is activated which then switches

the regulator output Off, would cause the RESET pin to go

low.

The RESET pin is an open collector output and requires an

external pull-up resistor to V

tor should be in the range of 10K

Ω to 200KΩ.

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