LTC3370 datasheet(16/44 Pages) LINER

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LTC3372

Rev. A

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PIN FUNCTIONS

is regulated proportionally lower. An internal 10μA pull-

up current source is connected to this pin. A capacitor to

ground at this pin sets the ramp time to the final regulated

output voltage. Alternatively, a resistor divider on another

voltagesupplyconnectedtothispinallowsthecontroller’s

output to track another supply during start-up.

VOUT/EXTVCC (Pin 43): HV Controller Output Voltage

Sensing and External VCC Power Input. Connect this pin

to the HV controller’s regulated output voltage. The HV

controller VOUT is regulated to either 3.3V or 5V by an

internal resistor divider selected by the VPROG pin. This

pin is also provides an external VCC connection and sup-

plies internal bias voltages from VOUT to improve low IQ

performance and reduce power loss.

SENSE– (Pin 44): HV Controller Negative (–) Input to

Differential Current Comparator. This SENSE– pin also

functions as the output voltage sense pin for a secondary

15% overvoltage protection in addition to the 7.5% over-

voltage protection at the VOUT/EXTVCC pin. In the situation

that SENSE– pin is separated from VOUT/EXTVCC pin to

achieve point-of-load (POL) regulation, SENSE– can begin

drawing a >500µA current when SENSE– is 200mV greater

than VOUT (VOUT = 5V) or INTVCC (VOUT = 3.3V). When

voltage on SENSE– pin is close to INTVCC, SENSE– can

begin drawing >500µA current. Do not connect a filtering

resistor in series with SENSE– pin unless SENSE– stays

close to ground in the application.

SENSE+ (Pin 45): HV Controller Positive (+) Input to

Differential Current Comparator. The ITH pin voltage and

controlled offsets between the SENSE– and SENSE+ pins

set the current trip threshold. The current comparator

can be used for either inductor DCR sensing or traditional

current sensing resistor (RSENSE) sensing.

ITH (Pin 46): HV Controller Error Amplifier Output and

Compensation Point. The current comparator threshold

increases with this control voltage.

VOUTPRG (Pin 47): HV Controller Output Voltage Program-

ming Pin. When this pin is tied to INTVCC, the output volt-

age is regulated to 5V. When tied to ground, the output

voltage is regulated to 3.3V.

PGOOD (Pin 48): HV Controller Power Good Open-Drain

Logic Output. This pin is pulled low when the voltage at the

VOUT/EXTVCC pin is outside of the ±7.5% window around

the regulated level, or voltage at SENSE– pin is more than

15% above the regulated level of VOUT.

GND (Exposed Pad Pin 49): Ground. The exposed pad

must be soldered to a continuous printed circuit board

ground plane directly under the IC package for rated ther-

mal performance. The exposed pad is a shared ground for

signal grounds, driver ground and power stage grounds

of all HV and LV buck regulators.

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