LTC3870_15 Datasheet, PDF (7/22 Pages) Linear Technology – PolyPhase Step-Down Slave Controller for LTC3880/LTC3883 with Digital Power System Management

LTC3870
Pin Functions
FAULT0/FAULT1 (Pin 26/Pin 25): Fault Input Pins. Con-
nect these pins to the master chip GPIO pins to respond
to fault signals from the master controller. If this pin is
low, both TG and BG pins are pulled down at the corre-
sponding channel. There is a 500k pull down resistor on
FAULT0/FAULT1 internally. These pins have to be driven
high externally for normal operation.
FREQ (Pin 27): Frequency Set Pin. There is a precision
10μA current flowing out of this pin. A resistor to ground
sets a voltage which in turn programs the frequency. This
pin sets the default switching frequency when there is no
external clock on the SYNC pin. Set the frequency close
to the external clock to help the internal PLL sync to the
SYNC pin clock quickly and smoothly. See the application
section for the detailed information.
SGND (Exposed Pad Pin 29): Signal Ground. All small-
signal and compensation components should connect to
this ground, which in turn connects to PGND at one point.
The exposed pad must be soldered to the PCB, providing
a local ground for the control components of the IC, and
be tied to PGND under the IC.
For more information www.linear.com/LTC3870
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