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LTM4650A

4650afb

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PIN FUNCTIONS

VOUT1(A1–A5,B1–B5,C1–C4):PowerOutputPins.Apply

outputloadbetweenthesepinsandGNDpins.Recommend

placing output decoupling capacitance directly between

these pins and GND pins. Review Table 6.

GND(A6–A7,B6–B7,D1–D4,D9–D12,E1–E4,E10–E12,

F1–F3, F10–F12, G1, G3, G10, G12, H1–H7, H9–H12,

J1, J5, J8, J12, K1, K5–K8, K12, L1, L12, M1 , M12):

Power Ground Pins for Both Input and Output Returns.

VOUT2 (A8–A12, B8–B12, C9–C12): Power Output Pins.

Apply output load between these pins and GND pins. Rec-

ommend placing output decoupling capacitance directly

between these pins and GND pins. Review Table 6.

VOUTS1, VOUTS2 (C5, C8): This pin is connected to the top

of the internal top feedback resistor for each output. The

pin can be directly connected to its specific output, or

connected to DIFFOUT when the remote sense amplifier

is used. In paralleling modules, one of the VOUTS pins is

connectedtotheDIFFOUTpininremotesensingordirectly

to VOUT with no remote sensing. It is very important to

connect these pins to either the DIFFOUT or VOUT since

this is the feedback path, and cannot be left open. See the

Applications Information section.

fSET (C6): Frequency Set Pin. A 10µA 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.

SGND(C7,D6,G6–G7,F6–F7):SignalGroundPin.Return

ground path for all analog and low power circuitry. Tie a

single connection to the output capacitor GND in the ap-

plication. See layout guidelines in Figure 14.

VFB1, VFB2 (D5, D7): The Negative Input of the Error Am-

plifier for Each Channel. Internally, this pin is connected

to VOUTS1 or VOUTS2 with a 60.4kΩ precision resistor.

Different output voltages can be programmed with an ad-

ditional resistor between VFBandGNDpins.InPolyPhase®

operation, tying the VFB pins together allows for parallel

operation. See the Applications Information section for

details. Do not drive this pin.

TRACK1, TRACK2 (E5, D8): Output Voltage Tracking Pin

and Soft-Start Inputs. Each channel has a 1.3µA pull-up

current source. When one channel is configured to be

master of the two channels, then a capacitor from this pin

to ground will set a soft-start ramp rate. The remaining

channel can be set up as the slave, and have the master’s

output applied through a voltage divider to the slave out-

put’s track pin. This voltage divider is equal to the slave

output’s feedback divider for coincidental tracking. See

the Applications Information section.

COMP1, COMP2 (E6, E7): Current control threshold and

error amplifier compensation point for each channel. The

current comparator threshold increases with this control

voltage. This device is internal compensated. See Applica-

tions Information section. Tie the COMP pins together for

parallel operation. Do not drive this pin.

DIFFP (E8): Positive input of the remote sense amplifier.

This pin is connected to the remote sense point of the

output voltage. Diffamp can be used for ≤3.3V outputs.

See the Applications Information section.

DIFFN (E9): Negative input of the remote sense amplifier.

This pin is connected to the remote sense point of the

output GND. Diffamp can be used for ≤3.3V outputs. See

the Applications Information section.

MODE_PLLIN (F4): Force Continuous Mode, Burst Mode

Operation, or Pulse-Skipping Mode Selection Pin and

External Synchronization Input to Phase Detector Pin.

Connect this pin to SGND to force both channels into

force continuous mode 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 both channels into continuous mode of

operation and synchronized to the external clock applied

to this pin.

RUN1, RUN2 (F5, F9): Run Control Pin. A voltage above

1.25V will turn on each channel in the module. A voltage

below 1.25V on the RUN pin will turn off the related chan-

nel. Each RUN pin has a 1µA pull-up current, once the

RUN pin reaches 1.2V an additional 4.5µA pull-up current

is added to this pin.

(Recommended to Use Test Points to Monitor Signal Pin Connections.)

PACKAGE ROW AND COLUMN LABELING MAY VARY

AMONG µModule PRODUCTS. REVIEW EACH PACKAGE

LAYOUT CAREFULLY.

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