ltc3612 Linear Technology Corporation, ltc3612 Datasheet - Page 9

• Manufacturer Part Number: ltc3612
• Description: 3a, 4mhz Monolithic Synchronous Step-down Dc/dc Converter
• Manufacturer: Linear Technology Corporation

PIN FUNCTIONS
PGOOD (Pin 16/Pin 3): Power Good. This open-drain
output is pulled down to SGND on start-up and while the
FB voltage is outside the power good voltage window. If
the FB voltage increases and stays inside the power good
window for more than 100μs the PGOOD pin is released.
If the FB voltage leaves the power good window for more
than 100μs the PGOOD pin is pulled down.
In DDR mode (DDR = V
in relation to the actual TRACK/SS pin voltage. During up/
down tracking the PGOOD pin is always pulled down.
In shutdown the PGOOD output will actively pull down
and may be used to discharge the output capacitors via
an external resistor.
MODE (Pin 17/Pin 4): Mode Selection. Tying the MODE
pin to SV
Mode operation (with an internal Burst Mode clamp),
respectively. If this pin is held at slightly higher than half
of SV
this pin to an external voltage selects Burst Mode opera-
tion with the burst clamp set to the pin voltage. See the
Operation section for more details.
V
the feedback voltage from the external resistive divider
across the output.
FB
(Pin 18/Pin 5): Voltage Feedback Input Pin. Senses
IN
, forced continuous mode is selected. Connecting
IN
or SGND enables pulse-skipping mode or Burst
IN
), the power good window moves
(QFN/FE)
ITH (Pin 19/Pin 6): Error Amplifi er Compensation. The
current comparator’s threshold increases with this control
voltage. Tying this pin to SV
tion and AVP mode.
TRACK/SS (Pin 20/Pin 7): Track/External Soft-Start/Ex-
ternal Reference. Start-up behavior is programmable with
the TRACK/SS pin:
1. Tying this pin to SV
2. External soft-start timing can be programmed with a
3. TRACK/SS can be used to force the LTC3612 to track
The pin can also be used as external reference input. See the
Applications Information section for more information.
Exposed Pad (Pin 21/Pin 21): Power Ground (PGND).
This pin connects to the source of the internal N-channel
power MOSFET. This pin should be connected close to the
(–) terminal of C
circuit.
capacitor to ground and a resistor to SV
the start-up behavior of another supply.
IN
and C
IN
OUT
selects the internal soft-start
IN
.
enables internal compensa-
LTC3612
IN
.
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