LTC2927CDDB-TR View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
LTC2927CDDB-TR Datasheet PDF : 16 Pages
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LTC2927
PI FU CTIO S TSOT/DFN Packages
GND (Pin 4/Pin 5): Device Ground.
TRACK (Pin 5/Pin 4): Tracking Control Input. A resistive
voltage divider between RAMPBUF and TRACK determines
the tracking profile of the slave supply. TRACK servos to
0.8V, and the current supplied at TRACK is mirrored at FB.
The TRACK pin is capable of supplying at least 1mA when
VCC = 2.9V. Under short circuit conditions, the TRACK pin
is capable of supplying up to 70mA. Do not connect to
GND for extended periods. Limit the capacitance at the
TRACK pin to less than 25pF.
RAMPBUF (Pin 6/Pin 3): Ramp Buffer Output. Provides
a low impedance buffered version of the signal on the
RAMP pin. This buffered output drives the resistive volt-
age divider that connects to the TRACK pin. Limit the
capacitance at the RAMPBUF pin to less than 100pF. Float
RAMPBUF if unused.
RAMP (Pin 7/Pin 2): Ramp Buffer Input. The RAMP pin is
the input to the voltage buffer whose output drives a resis-
tive voltage divider connected to the TRACK pin. Connect
this input to a capacitor to set the ramp voltage generated
from internal 10μA pull-up or pull-down currents. RAMP
can also be connected to an external ramping signal for
tracking. Ground RAMP if unused.
ON (Pin 8/Pin 1): On Control Input. The voltage level of
the ON pin relative to its 1.23V threshold (with 75mV
hysteresis) controls the tracking direction of the LTC2927.
An active high causes a 10μA pull-up current to flow at
the RAMP pin, which charges an external capacitor. An
active low at the ON pin causes a 10μA pull-down cur-
rent at the RAMP pin to discharge the external capacitor
relative to GND.
Exposed Pad (NA/Pin 9): Exposed pad may be left open
or connected to device ground.
W
FU CTIO AL BLOCK DIAGRA
RAMPBUF
5
ON
5
+
1.23V –
5
VCC
1x
VCC
10μA
RAMP
5
10μA
2.5V +
VCC –
TRACK
5
UVLO
VCC
0.8V
GND
5
0.2V
SDO
5
FB
5
2927 BD
2927fb
5
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