MIC2128 datasheet(14/32 Pages) MICROCHIP

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MIC2128

DS20005620A-page 14

 2016 Microchip Technology Inc.

3.0

PIN DESCRIPTION

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

3.1

Power Good Output Pin (PG)

Connect PG to VDD through a pull up resistor. PG is low

when the FB voltage is 10% below the 0.6V reference

voltage.

3.2

Current Limit Pin (ILIM)

Connect a resistor from ILIM to SW to set current limit.

Refer to Section 4.3 “Current Limit (ILIM)” for more

details.

3.3

Switch Pin (SW)

SW pin provides return path for the high-side

N-MOSFET gate driver when DH is low and is also

used to sense low-side MOSFET current by monitoring

the SW node voltage for negative current limit function.

Connect SW to the pin where high-side MOSFET

source and the low-side MOSFET drain terminal are

connected together.

3.4

Bootstrap Capacitor Pin (BST)

BST capacitor acts as supply for the high-side

N-MOSFET driver. Connect a minimum of 0.1 µF low

ESR ceramic capacitor between BST and SW. Refer to

Section 4.5 “High-Side MOSFET Gate Drive (DH)”

section for more details.

3.5

High-Side N-MOSFET Gate Driver

Output Pin (DH)

High-side N-MOSFET gate driver Output. Connect DH

to the gate of external high-side N-MOSFET.

3.6

Power Ground Pin (PGND)

PGND provides return path for the internal low-side

N-MOSFET gate driver output and also acts as

reference for current limit comparator. Connect PGND to

the external low-side N-MOSFET source terminal and

to the return terminal of PVDD bypass capacitor.

3.7

Low-Side N-MOSFET Gate Driver

Output Pin (DL)

Low-side N-MOSFET gate driver output. Connect to

the gate terminal of the external low-side N-MOSFET.

TABLE 3-1:

PIN FUNCTION TABLE

MIC2128

Symbol

Pin Function

Open-drain Power Good Output pin

2ILIM

Current Limit setting resistor connection pin

Switch Pin and Current Sense Input for negative current limit

BST

Bootstrap Capacitor Connection Pin

High-side N-MOSFET gate driver Output

6PGND

Power Ground

Low-side N-MOSFET gate driver output.

8PVDD

Internal high voltage LDO Output of the MIC2128

EXTVDD

Supply to the internal low voltage LDO

Enable Input

FREQ

Switching Frequency Programming Input

Soft-Start time setting capacitor connection pin

Feedback Input

AGND

Analog ground

VDD

Supply for the MIC2128 internal analog circuits

VIN

Supply Input for the internal high voltage LDO

Exposed Pad

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