Pin Descriptions

Pin No.

Pin Name

Description

1FB

Feedback Input Pin.

This pin is used to select the required output voltage. It can be connected to an external resis-

tor divider for a user selected voltage or to either the OUT or GND pins for a fixed voltage.

GND: 5V output

OUT: 3.3V output

Resistor Divider: 1.8V~5.5V range output

2

LBI

Low-Battery Comparator Input Pin.

This pin is connected to the internal low battery voltage comparator. If the voltage on this pin

is less than the REF voltage - nominally 1.3V - then the LBO output will be low.

3

LBO

Open-Drain Low Battery Comparator Output.

This pin is used to indicate a low battery condition and is connected to the low battery voltage

comparator output. Note that the pin will be in a high impedence condition when the device is

in the shutdown mode.

4

REF

Reference Voltage Output Pin.

This pin is the output from the voltage reference generator and should be connected to a

0.1

mF bypass capacitor.

5

SHDN

Shutdown Input Pin.

This pin is used to power down the device and place it into the shutdown mode.

High: Device in normal operating mode

Low: Device in shutdown mode

6

GND

Ground Pin.

7LX

Switching Output Pin.

This pin is the device switching output pin which is connected to the internal N-channel and

P-channel switching power MOSFET drain pins.

8

OUT

Power Output Pin.

This pin is the converter output pin. It also supplies bootstrap power to the device.

Absolute Maximum Ratings

Supply Voltage ........................................

-0.3V to 7.0V

Storage Temperature ...........................

-50°Cto125°C

Operating Temperature ..........................

-40°Cto85°C

Note: These are stress ratings only. Stresses exceeding the range specified under

²Absolute Maximum Ratings² may

cause substantial damage to the device. Functional operation of this device at other conditions beyond those listed

in the specification is not implied and prolonged exposure to extreme conditions may affect device reliability.

HT77S10/HT77S11

Rev. 1.00

3

February 3, 2010