LTM4650 datasheet(10/38 Pages) AD

10 / 38 page

LTM4652

Rev. 0

For more information www.analog.com

PIN FUNCTIONS

VOUT1 (Pins A1–A5, B1–B5, C1–C4): Power Output Pins.

Apply output load between these pins and GND pins.

Recommend placing output decoupling capacitance

directly between these pins and GND pins. Review Table 6.

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

E12, F1–F3, F10–F12, G1, G3, G10, G12, H1–H4, 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 (Pins A8–A12, B8–B12, C9–C12): Power Output

Pins. Apply output load between these pins and GND

pins. Recommend placing output decoupling capacitance

directly between these pins and GND pins. Review Table 6.

VOUTS1, VOUTS2 (Pins 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 connected to the DIFFOUT pin in remote sensing or

directly to VOUT with no remote sensing. It is very import-

ant 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 (Pin C6): Frequency Set Pin. A 9.5µA current is

sourced from this pin. A resistor from this pin to ground

sets a voltage that in turn programs the operating fre-

quency. Alternatively, this pin can be driven with a DC

voltage that can set the operating frequency. See the

Applications Information section.

SGND (Pins C7, D6, G6–G7, F6–F7): 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 30.

VFB1, VFB2 (Pins D5, D7): The Negative Input of the

Error Amplifier for Each Channel. Internally, this pin is

connected to VOUTS1 or VOUTS2 with a 60.4k precision

resistor. Different output voltages can be programmed

with an additional resistor between VFB and GND pins. In

PolyPhase® operation, tying the VFB pins together allows

for parallel operation. See the Applications Information

section for details. Do not drive this pin.

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

Pin and Soft-Start Inputs. Each channel has a 1.25µA

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 (Pins E6, E7): Current control threshold

and error amplifier compensation point for each chan-

nel. The current comparator threshold increases with this

control voltage. COMP pin internal has 10pF filter cap to

SGND. An external RC filter circuit is required for control

loop compensation. See Applications Information section.

Tie the COMP pins together for parallel operation. Do not

drive this pin.

DIFFP (Pin E8): Positive input of the remote sense ampli-

fier. 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 (Pin E9): Negative input of the remote sense ampli-

fier. 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 (Pin F4): Forced Continuous Mode or Pulse-

Skipping Mode Selection Pin and External Synchronization

Input to Phase Detector Pin. Connect this pin to SGND to

force both channels into forced continuous mode of oper-

ation. Connect to INTVCC to enable pulse-skipping mode

of 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.

Note that this module is designed to conduct bidirectional

output current. When pulse-skipping mode is selected,

there is no way for the control loop to command instan-

taneous inductor current below 0A except by deliberately

(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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