MCP1650 datasheet(12/28 Pages) MICROCHIP

12 / 28 page

MCP1650/51/52/53

DS21876A-page 12

 2004 Microchip Technology Inc.

3.0

PIN DESCRIPTIONS

The descriptions of the pins are listed in Table 3-1.

TABLE 3-1:

PIN FUNCTION TABLE

3.1

External Gate Drive (EXT)

EXT is the output pin that drives the external N-channel

MOSFET on and off during boost operation. EXT is

equal to GND for SHDN or UVLO conditions.

3.2

Circuit Ground (GND)

Connect the GND pin to circuit ground. See layout

guidelines for suggested grounding physical layout.

3.3

Current Sense (CS)

Input peak current is sensed on CS through the exter-

nal current sense resistor. When the sensed current is

converted to a voltage, the current sense threshold is

122 mV below VIN typical. If that threshold is exceeded,

the pulse is terminated asynchronously.

3.4

Feedback Input (FB)

Connect output voltage of boost converter through

external resistor divider to the FB pin for voltage

regulation. The nominal voltage that is compared to this

input for pulse termination is 1.22V.

3.5

Shutdown Input (SHDN)

The SHDN input is used to turn the boost converter on

and off. For normal operation, tie this pin high or to VIN.

To turn off the device, tie this pin to low or ground.

3.6

Low Battery Input (LBI)

LBI is the input pin for the low battery comparator.

When the voltage on this pin falls below the nominal

1.22V threshold setting, the LBO (Low Battery Output)

open-drain is active-low.

3.7

Low Battery Output (LBO)

LBO is an active-low, open-drain output capable of

sinking 10 mA when the LBI pin is below the threshold

voltage. LBO is high-impedance during SHDN or UVLO

conditions.

3.8

Power Good (PG)

PG is an active-high, open-drain output capable of

sinking 10 mA when the FB input pin is 15% below its

typical value or more than 15% above its typical value,

indicating that the output voltage is out of regulation.

PG is high impedance during SHDN or UVLO

condition.

3.9

Input Voltage (VIN)

VIN is an input supply pin. Tie 2.7V to 5.5V input power

source.

Pin No.

MCP1650

Pin No.

MCP1651

Pin No.

MCP1652

Pin No.

MCP1653

Symbol

Function

1111

EXT

External Gate Drive

2222

GND

Ground

3333

Current Sense

4444

Feedback Input

5556

SHDN

Shutdown

—

LBI

Low Battery Input

—7

—8

LBO

Low Battery Output

—

Power Good Output

888

VIN

Input Voltage

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