LTC3428_15 Datasheet, PDF (5/12 Pages) Linear Technology – 4A, 2MHz Dual Phase Step-Up DC/DC Converter in 3mm 3mm DFN

LTC3428
PIN FUNCTIONS
PGNDA, PGNDB (Pins 1, 10, 11 (Exposed Pad)): Power
Ground for the IC. Tie directly to local ground plane.
SWA (Pin 2), SWB (Pin 9): Phase B and Phase A Switch
Pins. The inductor and Schottky diodes for each phase
are connected to these pins. Minimize trace length to
reduce EMI.
V_OUT (Pin 3): Power Supply Output and Bootstrapped
Power Source for the IC. Connect low ESR output filter
capacitors from this pin to the ground plane.
SHDN (Pin 4): Shutdown Pin. Grounding this pin shuts
down the IC. Connect to a voltage greater than 1.5V to
enable.
V_C (Pin 5): Error Amp Output. A frequency compensation
network is connected to this pin to compensate the boost
converter loop.
FB (Pin 6): Feedback Pin. A resistor divider from V_OUT is
connected here to set the output voltage according to
V_OUT = 1.243 • (1 + R1 / R2)
AGND (Pin 7): Signal Ground for the IC. Connect to ground
plane near feedback resistor divider.
V_IN (Pin 8): Input Supply Pin. Bypass V_IN with a low ESR
ceramic capacitor of at least 4.7μF. X5R and X7R dielectrics
are preferred for their superior voltage and temperature
characteristics.
BLOCK DIAGRAM
FB
V_IN
FB
ERROR AMPLIFIER/SOFT-START
–
V_C
+ 1.243V
I_SENB
RAMP/
SLOPE COMP
CLK B
OSCILLATOR
SHDN
V_C
AGND
CLK A
RAMP/
SLOPE COMP
SHUTDOWN
I_SENA
5pF
–
–
PWM
COMP
+
CHANNEL B
CHANNEL A
CURRENT
LIMIT
I_SENB
PWM
LOGIC
DRIVER
TSD
+
–
PWM
COMP
–
PWM
LOGIC
DRIVER
CURRENT
LIMIT
I_SENA
V_OUT
SWB
PGNDB
SWA
PGNDA
3428 BD
3428fb
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