MCP1630-ESLASHMS datasheet(11/26 Pages) MICROCHIP

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DS21896B-page 11

MCP1630/MCP1630V

3.0

MCP1630 PIN DESCRIPTIONS

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

TABLE 3-1:

PIN FUNCTION TABLE

3.1

Error Amplifier Output Pin (COMP)

COMP is an internal error amplifier output pin. External

compensation is connected from the FB pin to the

COMP pin for control-loop stabilization. An internal

voltage clamp is used to limit the maximum COMP pin

voltage to 2.7V (typ.). This clamp is used to set the

maximum peak current in the power system switch by

setting a maximum limit on the CS input for Peak

Current mode control systems.

3.2

Error Amplifier Inverting Input

(FB)

FB is an internal error amplifier inverting input pin. The

output (voltage or current) is sensed and fed back to

the FB pin for regulation. Inverting or negative

feedback is used.

3.3

Current Sensing Input (CS)

CS is the current sense input pin used for cycle-by-

cycle control for Peak Current mode converters. The

MCP1630

typically

used

for

sensed

current

applications to reduce the current sense signal, thus

reducing power dissipation.

For

Voltage

mode

Average

Current

mode

applications, a ramp is used to compare the error

amplifier output voltage with producing the PWM duty

cycle. For applications that require higher signal levels,

the MCP1630V is used to increase the level from a

maximum of 0.9V (MCP1630) to 2.7V (MCP1630V).

The common mode voltage range for the MCP1630V

CS input is VIN-1.4V. For normal PWM operation, the

CS input should be less than or equal to VIN - 1.4V at

all times.

3.4

Oscillator Input (OSC)

OSC is an external oscillator input pin. Typically, a

microcontroller I/O pin is used to generate the OSC

input. When high, the output driver pin (VEXT) is driven

low. The high-to-low transition initiates the start of a

new cycle. The duty cycle of the OSC input pin deter-

mines the maximum duty cycle of the power converter.

For example, if the OSC input is low for 75% of the time

and high for 25% of the time, the duty cycle range for

the power converter is 0% to 75% maximum.

3.5

Ground (GND)

Connect the circuit ground to the GND pin. For most

applications, this should be connected to the analog or

quiet ground plane. Noise on this ground can affect the

sensitive cycle-by-cycle comparison between the CS

input and the error amplifier output.

3.6

External Driver Output Pin (VEXT)

VEXT is an external driver output pin, used to determine

the power system duty cycle. For high-power or high-

side drives, this output should be connected to the logic-

level input of the MOSFET driver. For low-power, low-

side applications, the VEXT pin can be used to directly

drive the gate of an N-channel MOSFET.

3.7

Input Bias Pin (VIN)

VIN is an input voltage pin. Connect the input voltage

source to the VIN pin. For normal operation, the voltage

on the VIN pin should be between +3.0V and +5.5V. A

0.1 µF bypass capacitor should be connected between

the VIN pin and the GND pin.

3.8

Reference Voltage Input (VREF)

VREF is an external reference input pin used to regulate

the output of the power system. By changing the VREF

input, the output (voltage or current) of the power sys-

tem can be changed. The reference voltage can range

from 0V to VIN (rail-to-rail).

DFN/MSOP

Name

Function

COMP

Error Amplifier Output pin

Error Amplifier Inverting Input

Current Sense Input pin (MCP1630) or Voltage Ramp Input pin (MCP1630V)

OSC IN

Oscillator Input pin

GND

Circuit Ground pin

6VEXT

External Driver Output pin

7VIN

Input Bias pin

8VREF

Reference Voltage Input pin

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