LT3077ACRZ-R7 datasheet(12/38 Pages) AD

12 / 38 page

Data Sheet

LT3077

analog.com

Rev. 0

12 of 38

SENSE

Kelvin Sense for OUT. The SENSE pin is the inverting input to the error amplifier.

Optimum regulation is obtained when the SENSE pin is connected to the OUT pins of

the regulator. However, in critical applications, the resistance of PCB traces between

the regulator and the load causes small voltage drops, creating a load regulation error

at the point of load. Connecting the SENSE pin to the load instead of directly to OUT

eliminates this voltage error.

9, 10, 15

GND

Ground. To ensure proper electrical and thermal performance, connect all GND pins of

the package to the PCB ground.

REF

Reference Filter. Bypassing the REF pin to GND with a 4.7µF capacitor decreases

output voltage noise and provides a soft-start function to the reference. ADI

recommends the use of a high-quality, low-leakage capacitor.

ILIM

Programmable Current Limit. The ILIM pin sources a current typically equal to

IOUT/3000. As a result, the current limit programming factor is 3A × kΩ/RILIM, where RILIM

is the resistor from ILIM to GND.

BIASF

Bias Filter Pin. The LT3077 requires a minimum 2.2µF bypass capacitor on this pin.

BIAS

Bias Supply. This pin supplies current to the internal control circuitry and the output

stage, driving the pass transistor. This pin doesn’t require any bypass capacitor. To

ensure proper operation, the BIAS voltage must satisfy the following conditions:

2.375V ≤ VBIAS ≤ 5.5V and VBIAS ≥ 1.2 + VOUT.

16, 17, 18 IN

Input Supply. The exposed pad consisting of pins 16-18 of the LFCSP-RT package are

the electrical connection to IN. These pins supply power to the high-current pass

transistor. Connect the entire IN exposed pad consisting of pins 16-18 for proper

electrical and thermal performance. The LT3077 requires a bypass capacitor at IN to

maintain stability and low input impedance over frequency. A 10µF input bypass

capacitor suffices for most battery and power plane impedances. Minimizing input

trace inductance optimizes performance. Applications with low VIN-VOUT differential

voltage and large, fast load transients may require much higher input capacitor to

prevent the input supply from drooping and allow the regulator to enter dropout.

A N A L O G D E V I C E S

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