MP2918

—4V TO 40V SYNCHRONOUS STEP-DOWN CONTROLLER

MP2918 Rev. 1.02

www.MonolithicPower.com

14

5/31/2017

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PIN FUNCTIONS

TSSOP-20

Pin #

QFN-20

Pin #

Name

Description

1

19

IN

Input supply. The MP2918 operates on a 4V to 40V input range. A

ceramic capacitor is needed to prevent large voltage spikes at the input.

2

20

EN/SYNC

Enable input. The EN/SYNC threshold is 1.22V with 130mV of

hysteresis. EN/SYNC is used to implement an input under-voltage lockout

(UVLO) function externally. If an external sync clock is applied to

EN/SYNC, the internal clock follows the sync frequency.

3

1

VCC2

External power supply for the internal VCC1 regulator. VCC2 disables

connect a power supply greater than 12V to VCC2. Connect VCC2 to an

external power supply to reduce power dissipation and increase efficiency.

4

2

VCC1

Internal bias supply. A

≥1µF decoupling capacitor is required between

VCC1 and PGND.

5

3

SGND

side of the output capacitors.

6

4

SS

Soft-start control input. SS is used to program the soft-start period with

an external capacitor between SS and SGND.

7

5

COMP

Regulation control loop compensation. Connect an R-C network from

COMP to SGND to compensate for the regulation control loop.

8

6

FB

Feedback. FB is the input of the error amplifier. An external resistive

divider connected between the output and SGND is compared to the

internal +0.8V reference to set the regulation voltage.

9

7

CCM/AAM

Continuous

conduction

mode/advanced

asynchronous

mode.

Floating CCM/AAM or connecting CCM/AAM to VCC1 makes the part

operate in CCM. Connecting an appropriate external resistor from

CCM/AAM to SGND (so AAM is at a low level) makes the part operate in

AAM. The AAM voltage should be no less than 480mV.

10

8

FREQ

Frequency. Connect a resistor between FREQ and SGND to set the

switching frequency.

11

9

PG

Power good output. The output of PG is an open drain.

12

10

ILIM

Sense voltage limit set. The voltage at ILIM sets the nominal sense

voltage at the maximum output current. There are three fixed options:

float, VCC1, and SGND.

13

11

SYNCO

Frequency synchronous out. SYNCO outputs a 180°out-of-phase clock

when the part works in CCM for dual-channel operation.

14

12

SENSE-

Negative input for the current sense. The sensed inductor current limit

threshold is determined by the status of ILIM.

15

13

SENSE+

Positive input for the current sense. The sensed inductor current limit

threshold is determined by the status of ILIM.

16

14

PGND

High-current ground reference for the internal low-side switch driver

and the VCC1 regulator circuit. Connect PGND to the negative terminal

of the VCC1 decoupling capacitor directly.