MIC2875 datasheet(12/24 Pages) MICROCHIP

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MIC2875

DS20005549A-page 12

 2015 Microchip Technology Inc.

4.0

FUNCTIONAL DESCRIPTION

4.1

Input (IN)

The input supply provides power to the internal

MOSFETs gate drivers and control circuitry for the

boost regulator. The operating input voltage range is

from 2.5V to 5.5V. A 1 μF low-ESR ceramic input

capacitor should be connected from IN to AGND as

close to MIC2875 as possible to ensure a clean supply

voltage for the device. A minimum voltage rating of 10V

is recommended for the input capacitor.

4.2

Switch Node (SW)

The MIC2875 has internal low-side and synchronous

MOSFET switches. The switch node (SW) between the

internal MOSFET switches connects directly to one

end of the inductor and provides the current path during

switching cycles. The other end of the inductor is

connected to the input supply voltage. Due to the

high-speed switching on this pin, the switch node

should be routed away from sensitive nodes wherever

possible.

4.3

Ground Path (AGND)

The ground path (AGND) is for the internal biasing and

control circuitry. AGND should be connected to the

PCB pad for the package exposed pad. The current

loop of the analog ground should be separated from

that of the power ground (PGND). AGND should be

connected to PGND and EP at a single point.

4.4

Power Ground (PGND)

The power ground (PGND) is the ground path for the

high current in the boost switches. The current loop for

the power ground should be as short as possible and

separate from the AGND loop as applicable.

4.5

Boost Converter Output (OUT)

A low-ESR ceramic capacitor of 22 μF (for operation

with VIN ≤ 5.0V), or 66 μF (for operation with VIN >

5.0V) should be connected from VOUT to PGND as

close as possible to the MIC2875. A minimum voltage

rating of 10V is recommended for the output capacitor.

4.6

Enable (EN)

Enable pin of the MIC2875. A logic high on this pin

enables the MIC2875. When this pin is driven low, the

MIC2875 enters the shutdown mode. When the EN pin

is left floating, it is pulled-down internally by a built-in

2.5 MΩ resistor.

4.7

Feedback/Output Voltage Sense

(FB/OUTS)

Feedback or output voltage sense pin for the boost

converter. For the fixed voltage version, this pin should

be connected to the OUT pin. For the adjustable

version, connect a resistor divider to set the output

voltage

(see

“Section 5.7

“Output

Voltage

Programming”

” for more information).

4.8

Power Good Output (/PG)

The open-drain active-low power-good output (/PG) is

low when the output voltage is above the power-good

threshold. A pull-up resistor of 1 MΩ is recommended.

4.9

Exposed Heat Sink Pad (EP)

The exposed heat sink pad, or ePad (EP), should be

connected to AGND for best thermal performance.

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