LTM8045 datasheet(14/54 Pages) AD

14 / 54 page

LTM4655

Rev. 0

For more information www.analog.com

PIN FUNCTIONS

VIN1 (A1–A3, B3): Channel 1 Power Input Pins. Apply

input voltage and input decoupling capacitance directly

between VIN1 and a power ground (PGND) plane. Either

connect PGND to VOUT1– in noninverting step-down appli-

cations, where VOUT1+ is the regulated positive output

voltage—or, connect PGND to VOUT1+ in inverting buck-

boost applications, where VOUT1– is the regulated negative

output voltage.

VIN2 (A6–A8, B8): Channel 2 Power Input Pins. Apply

input voltage and input decoupling capacitance directly

between VIN2 and a power ground (PGND) plane. Either

connect PGND to VOUT2– in noninverting step-down appli-

cations, where VOUT2+ is the regulated positive output

voltage—or, connect PGND to VOUT2+ in inverting buck-

boost applications, where VOUT2– is the regulated negative

output voltage.

VD1 (A4, B4, C4): Drain of Channel 1’s Primary Switching

MOSFET. Apply at least one 4.7μF high frequency ceramic

decoupling capacitor directly from VD1 to VOUT1–. Give

this capacitor higher layout priority (closer proximity to

the module) than any VIN1 decoupling capacitors.

VD2 (A9, B9, C9): Drain of Channel 2’s Primary Switching

MOSFET. Apply at least one 4.7μF high frequency ceramic

decoupling capacitor directly from VD2 to VOUT2–. Give

this capacitor higher layout priority (closer proximity to

the module) than any VIN2 decoupling capacitors.

SVIN1 (C3): Channel 1 Input Voltage Supplies for Small

Signal Circuits. SVIN1 is the input to the INTVCC1 LDO.

Connect SVIN1 directly to VIN1.

SVIN2 (C8): Channel 2 Input Voltage Supplies for Small

Signal Circuits. SVIN2 is the input to the INTVCC2 LDO.

Connect SVIN2 directly to VIN2.

SVINF1 (B11): Channel 1 Filtered Voltage Supply for Small

Signal Circuits. If powering the LTM4655’s 5V LDO from

channel 1’s supply for small signal circuits, electrically

connect SVINF1 and LDOIN with a short trace capable of

carrying up to 25mA.

SVINF2 (C11): Channel 2 Filtered Voltage Supply for Small

Signal Circuits. If powering the LTM4655’s 5V LDO from

channel 2’s supply for small signal circuits, electrically

connect SVINF2 and LDOIN with a short trace capable of

carrying up to 25mA.

LDOIN (B12): Input to 5V LDO. Connect LDOIN to either

SVINF1 or SVINF2 with a short trace capable of carrying up

to 25mA, depending on which input rail is better suited

for powering the 5V LDO. If LDOIN is being powered from

SVINF1 or SVINF2, no bypass capacitance from LDOIN to

GND is needed; otherwise, 0.1μF-to-1μF local bypass

capacitance is recommended.

VOUT1– (A5, B5, C5, D5, E5, F5, G4–5, H3, H5, J3–5,

K4–5, L4–5, M4–5): Negative Power Output of Channel 1.

Either connect VOUT1– to a PGND plane in noninverting

step-down applications, where VOUT1+ is the regulated

positive output voltage—or, connect VOUT1+ to PGND in

inverting buck-boost applications, where VOUT1– is the

regulated negative output voltage.

SVOUT1– (E4, G2, H2): Signal Return of Channel 1. The

SVOUT1– pins are the reference node for channel 1’s con-

trol loop. A small island of SVOUT1– copper should be

extended from the module and used to shield sensitive

channel 1 pins and signals from noise—such as those

routing to fSET1, ISET1a/b, and COMP1a/b. All SVOUT1–

pins are connected to each other internal to the module.

Connect Pin H2 to VOUT1– directly under the LTM4655.

The remaining SVOUT1– pins can be used for redundant

connectivity or routed to an ICT test point for design-

for-test considerations, as desired. See the Applications

Information section for the layout checklist.

VOUT1+ (K1–3, L1–3, M1–3): Positive Power Output of

Channel 1. Bypass VOUT1+ to VOUT1– local to the mod-

ule with at least 1μF. The remainder of VOUT1+ to VOUT1–

bypass caps should be located near channel 1’s load.

Either connect VOUT1+ to a PGND plane in inverting buck-

boost applications, where VOUT1– is the regulated nega-

tive output voltage—or, connect VOUT1– to a PGND plane

noninverting step-down applications, where VOUT1+ is the

regulated positive output voltage.

PACKAGE ROW AND COLUMN LABELING MAY VARY

AMONG µModule PRODUCTS. REVIEW EACH PACKAGE

LAYOUT CAREFULLY.

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