LTC3548-2
5
35482fb
TYPICAL PERFORMANCE CHARACTERISTICS
Effi ciency vs Load Current Effi ciency vs Load Current
T
A
= 25°C unless otherwise specifi ed.
V
OUT1
(Pin 1): Output Voltage Feedback for Channel 1. An
internal resistive divider divides the output voltage down
for comparison to the internal reference voltage.
RUN1 (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. This pin must be driven; do
not fl oat.
V
IN
(Pin 3): Input Power Supply. Must be closely decoupled
to GND.
SW1 (Pin 4): Regulator 1 Switch Node Connection to the
Inductor. This pin swings from V
IN
to GND.
GND (Pin 5): Ground. This pin is not connected internally.
Connect to PCB ground for optimum shielding.
MODE/SYNC (Pin 6): Combination Mode Selection and
Oscillator Synchronization. This pin controls the opera-
tion of the device. When tied to V
IN
or GND, Burst Mode
operation or pulse-skipping mode is selected, respectively.
Do not fl oat this pin. The oscillation frequency can be
synchronized to an external oscillator applied to this pin
and pulse-skipping mode is automatically selected.
SW2 (Pin 7): Regulator 2 Switch Node Connection to the
Inductor. This pin swings from V
IN
to GND.
POR (Pin 8): Power-On Reset. This common-drain logic
output is pulled to GND when the output voltage falls below
–8.5% of regulation and goes high after 117ms when both
channels are within regulation.
RUN2 (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. This pin must be driven; do
not fl oat.
V
FB2
(Pin 10): Output Feedback. Receives the feedback
voltage from the external resistive divider across the output.
Normal voltage for this pin is 0.6V.
Exposed Pad (GND) (Pin 11): Ground. Connect to the
(–) terminal of C
OUT
, and (–) terminal of C
IN
. Must be
connected to PCB ground for electrical contact and rated
thermal performance.
PIN FUNCTIONS
Effi ciency vs Load Current
LOAD CURRENT (mA)
1
EFFICIENCY (%)
100
95
90
85
80
75
70
65
60
10 100 1000
35482 G13
V
OUT2
= 1.5V
Burst Mode OPERATION
NO LOAD ON OTHER CHANNEL
CIRCUIT OF FIGURE 3
V
IN
= 2.7V
V
IN
= 4.2V
V
IN
= 3.6V
LOAD CURRENT (mA)
1
EFFICIENCY (%)
100
95
90
85
80
75
70
65
60
10 100 1000
35482 G14
V
OUT2
= 2.5V
Burst Mode OPERATION
NO LOAD ON OTHER CHANNEL
CIRCUIT OF FIGURE 3
V
IN
= 2.7V
V
IN
= 4.2V
V
IN
= 3.6V
LOAD CURRENT (mA)
1
EFFICIENCY (%)
100
95
90
85
80
75
70
65
60
10 100 1000
35482 G15
V
OUT2
= 3.3 V
Burst Mode OPERATION
NO LOAD ON OTHER CHANNEL
CIRCUIT OF FIGURE 3
V
IN
= 5V
