LTM4677 datasheet(7/34 Pages) LINER

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LTM4647

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PIN FUNCTIONS

VIN (A1-A3, B1-B2, C1-C2): Power Input Pins. Apply input

voltage between these pins and GND pins. Recommend

placing input decoupling capacitance directly between VIN

pins and GND pins.

GND (A4, A7, B3, C3, C4, D1-D4, E2-E4, F2, F4, F6, G1-

G4, H1-H5, J5-J7, K5-K7): Ground Pins for Both Input

and Output Returns. All ground pins need to connect with

large copper areas underneath the unit.

RUN (A6): Run Control Pin. A voltage above 1.35V will

turn on the module. This is a 1µA pull-up current on this

pin. Once the RUN pin rises above the 1.35V threshold

the pull-up current increases to 5µA.

PWM (B4): Control PWM Three-State Output Signal. For

monitor and test purpose only. Do not drive this pin.

CLKOUT (B5): Clock output with phase control using the

PHASMD pin to enable multiphase operation between

devices. See the Applications Information section.

TEST1, TEST2, TEST3 (B6, D5, F7): These pins are for

µModule initial test purposes. Please connect these pins

to GND with a large GND copper area.

MODE/PLLIN (B7): Mode Selection Pin and External

Synchronization Pin. Connect this pin to SGND to force

the module into force continuous current mode (CCM) of

operation. Connect to INTVCC to enable pulse-skipping

mode of operation. Leaving the pin floating will enable

Burst Mode operation. A clock on the pin will force the

module into continuous current mode of operation and

synchronized to the external clock applied to this pin. See

the Applications Information section.

SVIN (D6): Signal VIN. Input voltage to the internal 5.5V

regulator for the control circuitry of the regulator. Tie this

pin to VIN pin through a 2.2Ω plus 1µF R-C filter in most

application. See the Application Information section.

DRVCC (C5): Power Input Pin for the MOSFET driver cir-

cuitry. Connect to INTVCC output for the application with

the input voltage 6V and above or connect this pin to an

external supply 4.5V or above through a 2.2Ω plus 1µF

R-C filter. See the Application Information section.

INTVCC (C6): Internal 5.5V LDO for driving the control

circuitry decouple with pin to GND with a minimum of

2.2µF low ESR ceramic capacitor. The 5.5V LDO has a

10mA current limit.

PHASMD (C7): This pin determines the relative phases

between the internal controllers and the phasing of the

CLKOUT signal. See Table 2 in the Application Informa-

tion section.

FREQ (D7): Frequency Set Pin. A 20µA current is sourced

from this pin. A resistor from this pin to ground sets a

voltage that in turn programs the operating frequency.

Alternatively, this pin can be driven with a DC voltage

that can set the operating frequency. See the Applications

Information section.

HIZB(E5):PhaseSheddingInputPin.Whenthispinislow,

TRACK/SS, COMP and PWM pin go to high impedance.

Tie to INTVCC or VIN to disable this function.

VFB (E6): The Negative Input of the Error Amplifier. Inter-

nally, this pin is connected to VOSNS+ with a 60.4k 0.5%

precision resistor. Different output voltages can be pro-

grammed with an additional resistor between VFB and

VSNS– pins. In PolyPhase® operation, tying the VFB pins

together allows for parallel operation. See the Applications

Information section for details.

SGND (E7): Signal Ground Pin. Return ground path for all

analog and low power circuitry. Tie a single connection

to the output capacitor GND in the application. See layout

guidelines in Figure 22.

SW (F3): Switching node of the circuit is used for testing

purposes. Also an R-C snubber network can be applied

to reduce or eliminate switch node ringing, or otherwise

leave floating. See the Applications Information section.

TRACK/SS(F5):OutputVoltageTrackingPinandSoft-Start

Inputs. The pin has a 1.25µA pull-up current. A capacitor

from this pin to ground will set a soft-start ramp rate. In

tracking, the regulator output can be tracked to a different

voltage. The voltage ramp rate at his pin sets the voltage

ramp rate of the output. See the Applications Information

section.

PACKAGE ROW AND COLUMN LABELING MAY VARY

AMONG µModule PRODUCTS. REVIEW EACH PACKAGE

LAYOUT CAREFULLY.

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