LTM4608 LINER [Linear Technology], LTM4608 Datasheet - Page 7

• Manufacturer Part Number: LTM4608
• Description: Low VIN, 8A DC/DC ?ModuleTM with Tracking, Margining, and Frequency Synchronization
• Manufacturer: LINER [Linear Technology]

PIN FUNCTIONS
V
Pins. Apply input voltage between these pins and GND
pins. Recommend placing input decoupling capacitance
directly between V
V
Power Output Pins. Apply output load between these pins
and GND pins. Recommend placing output decoupling
capacitance directly between these pins and GND pins.
See Table 1.
GND (A1-A11, B1, B9-B11, F3, F7-F8, G1-G8): Power
Ground Pins for Both Input and Output Returns.
SV
nected to V
SGND (E1): Signal Ground Pin. Return ground path for all
analog and low power circuitry. Tie a single connection to
GND in the application.
MODE (B5): Mode Select Input. Tying this pin high enables
Burst Mode operation. Tying this pin low enables forced
continuous operation. Floating this pin or tying it to V
enables pulse-skipping operation.
CLKIN (B3): External Synchronization Input to Phase
Detector. This pin is internally terminated to SGND with a
50k resistor. The phase locked loop will force the internal
top power PMOS turn on to be synchronized with the
rising edge of the CLKIN signal. Connect this pin to SV
to enable spread spectrum modulation. During external
synchronization, make sure the PLLLPF pin is not tied to
V
PLLLPF (E3): Phase Locked Loop Lowpass Filter. An in-
ternal lowpass fi lter is tied to this pin. In spread spectrum
mode, placing a capacitor here to SGND controls the slew
rate from one frequency to the next. Alternatively, fl oat-
ing this pin allows normal running frequency at 1.5MHz,
tying this pin to SV
its normal frequency (2MHz), tying it to ground forces
the frequency to run at 0.67 times its normal frequency
(1MHz).
IN
OUT
IN
IN
(C1, C8, C9, D1, D3-D5, D7-D9 and E8): Power Input
or GND.
(F4): Signal Input Voltage. This pin is internally con-
(C10-C11, D10-D11, E9-E11, F9-F11, G9-G11):
IN
through a lowpass fi lter.
IN
IN
pins and GND pins.
forces the part to run at 1.33 times
IN
/2
IN
PHMODE (B4): Phase Selector Input. This pin determines
the phase relationship between the internal oscillator and
CLKOUT. Tie it high for 2-phase operation, tie it low for
3-phase operation, and fl oat or tie it to V
operation.
MGN (B8): Margining Pin. Tie this pin to V
margining. For margining, connect a voltage divider from
V
pin. Each resistor ≈ 50k. See Applications Information
and Figure 18.
BSEL (B7): Margining Bit Select Pin. Tying BSEL low selects
±5%, tying it high selects ±10%. Floating it or tying it to
V
TRACK (E5): Output Voltage Tracking Pin. Voltage track-
ing is enabled when the TRACK voltage is below 0.57V.
If tracking is not desired, then connect the TRACK pin to
SV
voltage needs to be below 0.18V before the chip shuts
down even though RUN is already low. Do not fl oat this
pin. A resistor divider and capacitor can be applied to the
TRACK pin to increase the soft-start time of the regulator.
See Applications Information. Can tie together for parallel
operation and tracking. Load current needs to be present
during track down.
FB (E7): The Negative Input of the Error Amplifi er. Internally,
this pin is connected to V
Different output voltages can be programmed with an ad-
ditional resistor between FB and GND pins. In PolyPhase
operation, tie FB pins together for parallel operation. See
Applications Information for details.
I
Compensation Point. The current comparator threshold
increases with this control voltage. Tie together in parallel
operation.
I
Amplifi er. Tie this pin to SGND for single phase operation.
For PolyPhase operation, tie the master’s I
while connecting all of the I
PolyPhase is a registered trademark of Linear Technology Corporation.
TH
THM
IN
IN
IN
/2 selects ±15%.
(F6): Current Control Threshold and Error Amplifi er
to GND with the center point connected to the MGN
. If TRACK is not tied to SV
(F5): Negative Input to the Internal I
OUT
THM
with a 10k precision resistor.
IN
pins together.
, then the TRACK pin’s
LTM4608
IN
/2 for 4-phase
TH
OUT
THM
Differential
to disable
to SGND
7
4608f
®