LTC7899 datasheet(13/50 Pages) AD

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Data Sheet

LTC7899

analog.com

Rev. 0

13 of 50

PGOOD

Power Good Open-Drain Logic Output. PGOOD is pulled to VIN- when the voltage on VFBB

is not within ±10% of its set point.

VFBB

Receives the remotely sensed feedback voltage for controller from an external resistor

to VIN−. This is the input to the Error Amplifier.

ITH

Error Amplifier Output and Switching Regulator Compensation Point. The current

comparator trip point increases with this control voltage.

VFBA

Input Power Supply Voltage Sense Pin. An external feedback resistor is tied from the

VFBA to VOUT. The pin voltage is regulated to the SENSE+ voltage.

SENSE-

The Negative (–) Input to the Differential Current Comparator. The ITH pin voltage and

controlled offsets between the SENSE– and SENSE+ pins in conjunction with RSENSE set

the current trip threshold.

SENSE+

The Positive (+) Input to the Differential Current Comparator. The SENSE+ pin supplies

current to the current comparator when it is greater than INTVCC. When SENSE+ is 3.2V

or greater, it supplies the majority of the sleep mode quiescent current instead of VBIAS,

further reducing the input-referred quiescent current.

DTCB

Dead Time Control Pin for TG Off to BG On Delay. Connect to VIN− to program an

adaptive TG falling to BG rising dead time delay of approximately 50ns. Connect to

INTVCC to program and adaptive TG falling to BG rising delay of approximately 30ns.

Connect a resistor between DTCB and VIN− to add additional delay (from 13ns to 100ns)

between the time TG falling and BG rising.

DTCA

Dead Time Control Pin for BG Off to TG On Delay. Connect to VIN− to program an

adaptive BG falling to TG rising dead time delay of approximately 50ns. Connect to

INTVCC to program an adaptive BG falling to TG rising dead time delay of

approximately 30ns. Connect a resistor between DTCA and VIN− to add additional delay

(from 13ns to 100ns) between the time BG falling and TG rising.

DRVSET

DRVCC Regulation Program pin. This pin sets the regulation point for the DRVCC low

dropout (LDO) linear regulator. Connect to VIN- to set DRVCC to 6.0V. Connect to INTVCC

to set DRVCC to 9.7V. Program voltages between 5V and 10V by placing a resistor (50k to

100k) between DRVSET and VIN-. The resistor and an internal 20µA source current

create a voltage used by the DRVCC LDO regulator to set the regulation point.

DRVUV

DRVCC UVLO and EXTVCC Switchover Program Pin. DRVUV determines the DRVCC UVLO

and EXTVCC switchover rising and falling thresholds, as listed in Table 1.

RUN

Run Control Input for the Controller. Forcing the RUN pin below 1.1V disables control,

while forcing the RUN pin below 0.7V shuts down the entire LTC7899, reducing

quiescent current to approximately 1µA. Tie the RUN pin to VBIAS for always-on

operation.

VIN- (EPAD)

Negative Input Voltage. The exposed pad must be soldered to PCB VIN- for rated

electrical and thermal performance.

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