LTC3407A
5
3407afa
Effi ciency vs Load Current Effi ciency vs Load Current Load Regulation
TYPICAL PERFORMANCE CHARACTERISTICS
Effi ciency vs Load Current Effi ciency vs Load Current Line Regulation
T
A
= 25°C unless otherwise specifi ed.
V
FB1
(Pin 1): Output Feedback. Receives the feedback volt-
age from the external resistive divider across the output.
Nominal voltage for this pin is 0.6V.
RUN/SS1 (Pin 2): Regulator 1 Enable and Soft-Start Input.
Forcing this pin to V
IN
enables regulator 1, while forcing it
to GND causes regulator 1 to shut down. Connect external
RC-network with desired time-constant to enable soft-start
feature. This pin must be driven; do not fl oat.
V
IN
(Pin 3): Main 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): Main Ground. Connect to the (–) terminal
of C
OUT
, and (–) terminal of C
IN
.
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.
PIN FUNCTIONS
LOAD CURRENT (mA)
1
0
EFFICIENCY (%)
30
20
10
70
60
50
40
100
90
80
10 100 1000
3407A G11
2.7V
V
OUT
= 2.5V Burst Mode OPERATION
CIRCUIT OF FIGURE 3
3.3V
4.2V
LOAD CURRENT (mA)
1
0
EFFICIENCY (%)
30
20
10
70
60
50
40
100
90
80
10 100 1000
3407A G12
Burst Mode OPERATION
PULSE SKIP MODE
V
IN
= 3.6V, V
OUT
= 1.8V
NO LOAD ON OTHER CHANNEL
LOAD CURRENT (mA)
1
–4
V
OUT
ERROR(%)
–3
1
0
–1
–2
4
3
2
10 100 1000
3407A G13
Burst Mode OPERATION
PULSE SKIP MODE
V
IN
= 3.6V, V
OUT
= 1.8V
NO LOAD ON OTHER CHANNEL
LOAD CURRENT (mA)
1
0
EFFICIENCY (%)
30
20
10
70
60
50
40
100
90
80
10 100 1000
3407A G14
2.7V
4.2V
V
OUT
= 1.2V Burst Mode OPERATION
3.3V
LOAD CURRENT (mA)
1
0
EFFICIENCY (%)
30
20
10
70
60
50
40
100
90
80
10 100 1000
3407A G15
2.7V
4.2V
3.3V
V
OUT
= 1.5V Burst Mode OPERATION
V
IN
(V)
2
V
OUT
ERROR (%)
0.5
0.4
0.3
0.2
0.1
0
–0.1
–0.2
–0.3
–0.4
–0.5
4
6
3407A G16
35
V
OUT
= 1.8V
I
OUT
= 200mA
