Internal 5V rail

EN

6V

3 PA

VIN

0.1 PF

AGND

1

6

LM5116WG

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SNVS599D – OCTOBER 2008 – REVISED FEBRUARY 2013

Figure 28. Input Blocking Diode for VCCX > VIN

In high voltage applications extra care should be taken to ensure the VIN pin does not exceed the absolute

maximum voltage rating of 100V. During line or load transients, voltage ringing on the VIN line that exceeds the

Absolute Maximum Ratings can damage the IC. Both careful PC board layout and the use of quality bypass

capacitors located close to the VIN and GND pins are essential.

Enable

The LM5116WG contains an enable function allowing a very low input current shutdown. If the enable pin is

pulled below 0.5V, the regulator enters shutdown, drawing less than 10 µA from the VIN pin. Raising the EN

input above 3.3V returns the regulator to normal operation. The maximum EN transition time for proper operation

is one switching period. For example, the enable rise time must be less than 4

μs for 250 kHz operation.

A 1 M

Ω pull-up resistor to VIN can be used to interface with an open collector control signal. At low input voltage

the pull-up resistor may be reduced to 100 k

Ω to speed up the EN transition time. The EN pin can be tied directly

to VIN if this function is not needed. It must not be left floating. If low-power shutdown is not needed, the UVLO

pin should be used as an on/off control.

Figure 29. Enable Circuit

Figure 30. EN Bias Current vs Voltage

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