LTM4641
PIN FUNCTIONS
the remote-sense connections prior to powering up the
the LTM4641 control loop drives the differential voltage
+
+
–
LTM4641. V
can also be connected as a redundant
between V
and V
to the lesser of TRACK/
ORB
OSNS
OSNS
is connected to V
). A resistor may be needed from
for some output voltage settings. (See
+
+
+
SS and 0.6V. V
internal to
feedbackconnectiontoV
ontheuser’smotherboard.
OSNS
the module (see V
ORB
OSNS
+
–
–
ORB
V
(D2): V
Readback Pin. This pin connects to
ORB
V
OSNS
+
–
V
to V
–
OSNS
OSNS
internaltotheµModuleregulator.Itisrecommended
OSNS
the Applications Information section: Setting the Output
Voltage.) Minimize stray capacitance to this pin to protect
the integrity of the output voltage feedback signal.
+
to route this pin (differentially with V
) to a test point
ORB
so as to allow the user a way to confirm the integrity of
the remote-sense connections prior to powering up the
–
–
V
OSNS
(H2): Negative Input to the Remote Sense Dif-
LTM4641. V
feedbackconnectiontoV
can also be connected as a redundant
ORB
–
ferential Amplifier. This pin connects to the negative side
of the output voltage remote sense point (GND potential)
ontheuser’smotherboard.
OSNS
OTBH (D3): Overtemperature Behavior Programming
Pin. When an overtemperature condition is detected (see
TEMP), HYST pulls logic low to inhibit switching. If OTBH
is connected to SGND, the LTM4641 latches HYST low. If
OTBHisleftfloating,outputvoltageregulationcanresume
when the overtemperature event clears.
via a resistor (R
). When switching action is on,
SET1B
the LTM4641 control loop drives the differential voltage
+
–
between V
and V
to the lesser of TRACK/
OSNS
SS and 0.6V. V
OSNS
–
–
is connected to V
). A resistor may be needed from
internal to
OSNS
ORB
–
the module (see V
ORB
+
–
V
to V
for some output voltage settings. (See
OSNS
OSNS
the Applications Information section.) Minimize stray ca-
pacitance to this pin to protect the integrity of the output
voltage feedback signal.
TꢁR(D4):TimeoutDelayTimerandPower-OnReset(POR)
Programming Pin. Connect a capacitor (C
) from TMR
TMR
toSGNDtoprogramthePORandtimeoutdelaytimeofthe
LTM4641; 9ms delay time per nanofarad of capacitance.
The minimum delay time is ~90μs, when TMR is left
electrically open circuit. Even though they use the same
capacitor, the power-on reset and timeout delay timers
operate independently of each other. Any nonlatching fault
or latching fault will reset the respective timer to the full
delay time without impacting the other timer.
SW (H10): Switching Node of the Power Stage. Mainly
used for testing purposes, however, one may optionally
connect a snubber (series-configured capacitor C and
SW
resistorR )fromSWtoGNDtoreduceradiatedEMI—in
SW
exchange for a minor compromise to power conversion
efficiency. (See the Applications Information section.)
COꢁP(J1):CurrentControlThresholdandErrorAmplifier
CompensationPoint.Thecurrentcomparatorthresholdof
LTM4641’s valley current mode control loop—and corre-
spondingly, the commanded trough of the power inductor
current—increasesasthiscontrolvoltageincreases.Itcan
be useful to make COMP available for observation on a
PCB via or test pad with an oscilloscope probe. However,
straycapacitanceandtracelengthstothissensitiveanalog
node should be minimized.
The timeout delay time programmed by a C
capacitor
TMR
can be negated by pulling TMR to INTV .
CC
RUN (D5): Run (On/Off) Control Pin. A RUN pin voltage
below 0.8V will turn off the module. A voltage above 2V
will command the module to turn on, if HYST is not as-
. The LTM4641 contains a moderate
(10k) pull-up resistor from HYST to INTV , and a pull-up
Schottky diode from RUN to HYST (see Figure 1). When
RUN is pulled logic low, HYST is pulled logic low via the
internal Schottky diode. RUN is compatible with direct-
drive (totem-pole output drive) as well as open-collector/
open-drain interfaces.
serted low by M
HYST
CC
f
(J2): Switching Frequency Setting and Adjustment
SET
Pin. ThispininterfacesdirectlytotheI pinofLTM4641’s
ON
internal control IC. Current flow into the I pin programs
ON
theon-timeofthecontrolloop’sone-shottimerandpower
control MOSFET, M . Minimize stray capacitance and
+
TOP
V
OSNS
(H1): Positive Input to the Remote Sense Differ-
ential Amplifier. This pin connects to the positive side of
any tracelengths to this pin.
the output voltage remote sense point (V
potential) via
). When regulating the output voltage,
For applications requiring regulated output voltages of 3V
or less at any time including during voltage rail tracking,
4641f
OUT
a resistor (R
SET1A
12
Linear [ Linear ]
