EN

LM5002

STANDBY

R2

OFF

OFF

STANDBY

R1

1.26V

0.45V

EN

LM5002

Disable PWM Controller

R1

Disable VCC Regulator

VIN

1.26V

0.45V

6 PA

R2

R2 =

1.26V

R1 =

LM5002

SNVS496D – JANUARY 2007 – REVISED MARCH 2013

www.ti.com

(2)

where

•

•

(3)

would set R1 to 29.4 k

Ω and R2 to 2.49 kΩ. The voltage at the EN pin should not exceed 10V unless the current

into the 6V protection Zener diode is limited below 4 mA. The EN pin voltage should not exceed 14V at any time.

Be sure to check both the power and voltage rating (some 0603 resistors are rated as low as 50V) for the

selected R1 resistor.

Figure 18. Basic EN (UVLO) Configuration

Remote configuration of the controller’s operational modes can be accomplished with open drain device(s)

connected to the EN pin as shown in Figure 19. A MOSFET or an NPN transistor connected to the EN pin can

force the regulator into the low power ‘off’ state. Adding a PN diode in the drain (or collector) provides the offset

to achieve the standby state. The advantage of standby is that the VCC LDO is not disabled and external

circuitry powered by VCC remains functional.

Figure 19. Remote Standby and Disable Control

12

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