LTC3619B_15 Datasheet, PDF (6/20 Pages) Linear Technology – 400mA/800mA Synchronous Step-Down DC/DC with Average Input Current Limit

LTC3619B
Typical Performance Characteristics T_A = 25°C, V_IN = 5V, unless otherwise noted.
Average Input Current Limit
vs Temperature
8
V_IN = 5V
6 ^{ILIM = 475mA}
4
Load Step (Channel 1)
V_OUT
200mV/DIV
AC-COUPLED
2
0
–2
–4
–6
–8
–50 –25
I_L
500mA/DIV
I_LOAD
500mA/DIV
0 25 50 75
TEMPERATURE (°C)
100 125
3619B G19
20µs/DIV
V_IN = 5V, V_OUT = 3.3V
I_LOAD = 0A TO 400mA
C_L = 4.7µF
Load Step (Channel 1)
V_OUT
200mV/DIV
AC-COUPLED
I_L
500mA/DIV
I_LOAD
500mA/DIV
3619B G20
20µs/DIV
V_IN = 5V, V_OUT = 1.8V
I_LOAD = 40mA TO 400mA
C_L = 4.7µF
3619B G21
Pin Functions (DD/MSE)
V_FB1 (Pin 1/Pin 1): Regulator 1 Output Feedback. Receives
the feedback voltage from the external resistive divider
across the regulator 1 output. Nominal voltage for this
pin is 0.6V.
RUN1 (Pin 2/Pin 2): Regulator 1 Enable. Forcing this pin
to V_IN enables regulator 1, while forcing it to GND causes
regulator 1 to shut down.
RLIM (Pin 3/Pin 3): Average Input Current Limit Program
Pin. Place a resistor and capacitor in parallel from this
pin to ground.
PGOOD1 (Pin 4/Pin 4): Open-Drain Logic Output. PGOOD1
is pulled to ground if the voltage on the V_FB1 pin is not
within power good threshold.
SW1 (Pin 5/Pin 5): Regulator 1 Switch Node Connection
to the Inductor. This pin swings from V_IN to GND.
V_IN (Pin 6/Pin 6): Main Power Supply. Must be closely
de-coupled to GND.
SW2 (Pin 7/Pin 7): Regulator 2 Switch Node Connection
to the Inductor. This pin swings from V_IN to GND.
PGOOD2 (Pin 8/Pin 8): Open-Drain Logic Output. PGOOD2
is pulled to ground if the voltage on the V_FB2 pin is not
within power good threshold.
RUN2 (Pin 9/Pin 9): Regulator 2 Enable. Forcing this pin
to V_IN enables regulator 2, while forcing it to GND causes
regulator 2 to shut down.
V_FB2 (Pin 10/Pin 10): Regulator 2 Output Feedback.
Receives the feedback voltage from the external resistive
divider across the regulator 2 output. Nominal voltage for
this pin is 0.6V.
GND (Pin 11/Pin 11): Ground. Bottom Exposed Pad. Con-
nect to the (–) terminal of C_OUT, and the (–) terminal of
C_IN. The Exposed Pad must be soldered to PCB.
3619bfb
6