LTM4613 datasheet(10/28 Pages) AD

10 / 28 page

LTM8060

Rev. 0

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PIN FUNCTIONS

VIN1 (Bank 6): Input power for the channel 1 regulator. The

VIN1 powers the internal control circuitry for channel 1/2

and is monitored by undervoltage lockout circuitry. The

VIN1 voltage must be greater than 3V for either chan-

nel 1/2 of the LTM8060 to operate. Decouple VIN1 to

ground with an external, low ESR capacitor. See Table 1

for recommended values.

VIN2 (Bank 4): Input power for the channel 2 regulator.

Decouple VIN2 to ground with an external, low ESR capaci-

tor. See Table 1 for recommended values.

VIN34 (Bank 5): Input power for the channel 3/4 regulator.

The VIN34 bank powers the internal control circuitry for

both channel 3/4 and is monitored by undervoltage lock-

out circuitry. The VIN34 voltage must be greater than 3V for

either channel 3/4 of the LTM8060 to operate. Decouple

VIN34 to ground with an external, low ESR capacitor. See

Table 1 for recommended values.

GND (Bank 2): Tie these GND pins to a local ground plane

below the LTM8060 and the circuit components. In most

applications, the bulk of the heat flow out of the LTM8060

is through these pads, so the printed circuit design has a

large impact on the thermal performance of the part. See

the PCB Layout and Thermal Considerations sections for

more details. Return the feedback divider (RFB) to this net.

VOUT1/2/3/4 (Banks 8/3/1/7): Power Output for

Channel 1/2/3/4, Respectively. Apply the output filter

capacitor and the output load between these pins and

GND plane.

AUX1/2/3/4 (Pins N10/L10/C2/E2): Low Current Voltage

Source for BIAS. In many designs, the BIAS pin is simply

connected to VOUT by way of the AUX pin. The AUXn pins

are internally connected to VOUTn and placed adjacent

to the BIASn pins to ease printed circuit board routing.

Although these pins are internally connected to VOUT, it

is not intended to deliver a higher current, so do NOT

connect these pins to the load. If thess pins are not tied

to BIAS, leave it floating.

BIAS12/34 (Pins M10/D2): The internal regulator will

draw current from BIASn instead of VIN1 or VIN34 when

BIASn is tied to a voltage higher than 3.2V. For output

voltages of 3.3V and above these pins should be tied to

VOUTn. If these pins are tied to a supply other than VOUTn

use a local bypass capacitor on these pins.

SYNC12/34 (Pins C11/N1): External Clock Synchronization

Input. Ground these pins for low ripple Burst Mode®

operation at low output loads; this will also disable the

CLKOUT function. Apply a DC voltage between 2.8V and

4V for forced continuous mode operation with spread

spectrum modulation. Float the SYNCn pin for forced

continuous mode operation without spread spectrum

modulation. Apply a clock source to the SYNCn pin for

synchronization to an external frequency. The LTM8060

will be in forced continuous mode when an external fre-

quency is applied.

CLKOUT12/34 (Pins C10/N2): Synchronization Output.

When SYNC12/34 > 2.8V, the CLKOUT12/34 pins pro-

vide a waveform about 90 degrees out-of-phase with

Channel 1/3, respectively. This allows synchronization with

other regulators with up to four phases. When an external

clock is applied to the SYNC12/34 pins, the CLKOUT12/34

pins will output a waveform with about the same phase,

duty cycle, and frequency as the SYNC12/34 waveform.

In Burst Mode operation, the CLKOUT12/34 pins will be

internally grounded. Float these pin if the CLKOUT12/34

function is not used. Do not drive these pins.

FB1/2/3/4 (Pins K11/K10/F1/F2): The LTM8060 regulates

the FBn pin to 800mV. Connect the feedback resistor to

this pin to set the output voltage.

RT12/34 (Pins L11/E1): Connect a resistor between RTn

and ground to set the switching frequency. Do not drive

these pins.

RUN1/2/3/4 (Pins E11/D11/L1/M1): The corresponding

channel of the LTM8060 is shutdown when these pins

are low and active when these pins are high. Tie to VINn if

shutdown feature is not used. An external resistor divider

from VINn can be used to program a VINn threshold below

which the corresponding channel of the LTM8060 will

shut down. Do not float these pins.

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