LTM8045 datasheet(6/22 Pages) AD

6 / 22 page

LTM4693

Rev. 0

For more information www.analog.com

PACKAGE ROW AND COLUMN LABELING MAY VARY

AMONG µModule PRODUCTS. REVIEW EACH PACKAGE

LAYOUT CAREFULLY.

PIN FUNCTIONS

GND (Pins A1, B1, A3, B3, C3, A5, B5): Power Ground

Connection. These pins and exposed thermal pad must

make full connection to PCB ground plane to meet specific

thermal requirements.

SW1 (Pins A2, B2, C2): Buck-Boost Converter Switching

Node Pin 1.

SW2 (Pins A4, B4, C4): Buck-Boost Converter Switching

Node Pin 2.

VIN (Pins C1, D1, D2): Power Input for Buck-Boost

Converter. Connect a minimum 22μF low ESR capacitor

to GND as close to the device as possible.

VOUT (Pins C5, D4, D5): Power Output for Buck-Boost

Converter. Connect a minimum 22μF low ESR capacitor

to GND as close to the device as possible. Capacitor value

may change depending on VOUT voltage and load current

requirements.

SS (Pin D3): External Soft-Start. Connect to VIN for 2ms

default soft-start period. Connect an external capacitor to

set soft-start period according to Equation 1.

tSS (ms) = 0.8 • CSS (nF)

(1)

RUN/UVLO (Pin E1): Input to Enable the IC. Connect

RUN to VIN to enable the LTM4693 at the 2.6V minimum

operating voltage. Connect to an external divider from VIN

to provide a programmable accurate VIN undervoltage

threshold, see application information for details.

MODE/SYNC (Pin E2): Mode Selection and Oscillator

Synchronization. Do not leave this pin floating.

MODE/SYNC = High (VIN). Disable Burst Mode opera-

tion and maintain low noise, constant frequency

PWM operation.

MODE/SYNC = Low (GND). The converter operates in

Burst Mode operation.

MODE/SYNC = External CLK. The internal oscillator is syn-

chronized to the external CLK signal, Burst Mode opera-

tion is disabled. A clock pulse width between 75ns and

tperiod –75ns is required to synchronize the oscillator. An

external resistor must be connected between FREQ and

GND to program the oscillator 25% to 50% below the

desired synchronization frequency.

FREQ (Pin E3): Oscillator Frequency Programming Input.

Default switching frequency is 1MHz when this pin is left

floating. Connect an external RT resistor from FREQ to

GND to program the switching frequency from 1MHz to

4MHz according to Equation 2.

RT (kΩ) =

110

fSW (MHz) – 1

(2)

FB (Pin E4): Feedback Input to Error Amplifier. The resis-

tor connected to this pin sets the converter output voltage

(Equation 3).

VOUT = 1.0V •

RFB + 60.4k

RFB

(3)

COMP (Pin E5): The output of the voltage error ampli-

fier used to program average inductor current inside the

module. An R-C from this pin to ground sets the voltage

loop compensation.

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