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LTC3407EDD-4#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
LTC3407-4
4
34074fa
TYPICAL PERFORMANCE CHARACTERISTICS
Effi ciency vs Input Voltage
Oscillator Frequency vs
Temperature
Oscillator Frequency Deviation
vs Supply Voltage
Reference Voltage vs
Temperature R
DS(ON)
vs Input Voltage R
DS(ON)
vs Temperature
Effi ciency vs Load Current Effi ciency vs Load Current Load Regulation
INPUT VOLTAGE (V)
2
50
EFFICIENCY (%)
55
65
70
75
100
85
3
4
34074 G04
60
90
95
80
5
6
LOAD = 100mA
LOAD = 800mA
LOAD = 1mA
LOAD = 10mA
V
OUT
= 1.8V
Burst Mode OPERATION
2.5
2.4
2.3
2.2
2.1
2.0
FREQUENCY (MHz)
TEMPERATURE (°C)
–50 25 75
34074 G05
–25 0
50 100 125
V
IN
= 3.6V
10
8
6
4
2
0
–2
–4
–6
–8
–10
FREQUENCY DEVIATION (%)
SUPPLY VOLTAGE (V)
2
34074 G06
3
456
0.615
0.610
0.605
0.600
0.595
0.590
0.585
REFERENCE VOLTAGE (V)
TEMPERATURE (°C)
–50 25 75
34074 G07
–25 0
50 100 125
V
IN
= 3.6V
V
IN
(V)
1
500
450
400
350
300
250
200
46
34074 G08
2
3
57
R
DS(ON)
(mΩ)
MAIN
SWITCH
SYNCHRONOUS
SWITCH
TEMPERATURE (°C)
–50
550
500
450
400
350
300
250
200
150
100
25 75
34074 G09
–25 0
50 100 150125
R
DS(ON)
(mΩ)
MAIN SWITCH
SYNCHRONOUS SWITCH
V
IN
= 3.6V
V
IN
= 4.2V
V
IN
= 2.7V
LOAD CURRENT (mA)
1
80
EFFICIENCY (%)
90
100
10 100 1000
LTC1273/75/76 • F25
70
75
85
95
65
60
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
V
OUT
= 2.5V
Burst Mode OPERATION
NO LOAD ON OTHER CHANNEL
LOAD CURRENT (mA)
1
EFFICIENCY (%)
90
100
10 100 1000
34074 G11
80
70
60
Burst Mode
OPERATION
PULSE-SKIPPING
MODE
V
IN
= 3.6V, V
OUT
= 1.8V
NO LOAD ON OTHER CHANNEL
LOAD CURRENT (mA)
1
0
V
OUT
ERROR (%)
2
4
10 100 1000
34074 G12
–2
–1
1
3
–3
–4
Burst Mode
OPERATION
PULSE-SKIPPING
MODE
V
IN
= 3.6V, V
OUT
= 1.8V
NO LOAD ON OTHER CHANNEL
LTC3407-4
5
34074fa
TYPICAL PERFORMANCE CHARACTERISTICS
Effi ciency vs Load Current Effi ciency vs Load Current Line Regulation
LOAD CURRENT (mA)
1
40
EFFICIENCY (%)
50
60
70
80
10 100 1000
34074 G13
30
20
10
0
90
100
V
IN
= 2.7V
V
IN
= 4.2V
V
IN
= 3.6V
V
OUT
= 1.2V
Burst Mode OPERATION
NO LOAD ON OTHER CHANNEL
LOAD CURRENT (mA)
1
EFFICIENCY (%)
90
100
10 100 1000
34074 G14
80
70
60
V
IN
= 2.7V
V
IN
= 4.2V
V
IN
= 3.6V
V
OUT
= 1.5V
Burst Mode OPERATION
NO LOAD ON OTHER CHANNEL
V
IN
(V)
2
V
OUT
ERROR (%)
0
0.2
0.4
6
34074 G15
–0.4
–0.2
–1.0
3
4
5
–0.6
–0.8
0.8
0.6
V
OUT
= 1.8V
I
OUT
= 200mA
T
A
= 25°C
PIN FUNCTIONS
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.
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): 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): Ground. This pin is not connected internally.
Connect to PCB ground for 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 is not
within ±8.5% of regulation and goes high after 29ms 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.
Nominal voltage for this pin is 0.6V.
Exposed Pad (GND) (Pin 11): Power Ground. Connect to
the (–) terminal of C
OUT
, and (–) terminal of C
IN
. Must be
connected to electrical ground on PCB.
LTC3407-4
6
34074fa
BLOCK DIAGRAM
OPERATION
The LTC3407-4 uses a constant frequency, current mode
architecture. The operating frequency is set at 2.25MHz
and can be synchronized to an external oscillator. Both
channels share the same clock and run in-phase. To suit a
variety of applications, the selectable Mode pin allows the
user to choose between low noise and high effi ciency.
The output voltage is set by an external divider returned
to the V
FB
pins. An error amplifi er compares the divided
output voltage with a reference voltage of 0.6V and adjusts
the peak inductor current accordingly. Overvoltage and
undervoltage comparators will pull the POR output low if
the output voltage is not within ±8.5%. The POR output
will go high after 2
16
clock cycles (about 29ms in pulse-
skipping mode) of achieving regulation.
Main Control Loop
During normal operation, the top power switch (P-channel
MOSFET) is turned on at the beginning of a clock cycle
when the V
FB
voltage is below the the reference voltage.
The current into the inductor and the load increases until
the current limit is reached. The switch turns off and
energy stored in the inductor fl ows through the bottom
switch (N-channel MOSFET) into the load until the next
clock cycle.
The peak inductor current is controlled by the internally
compensated I
TH
voltage, which is the output of the er-
ror amplifi er. This amplifi er compares the V
FB
pin to the
0.6V reference. When the load current increases, the
V
FB
voltage decreases slightly below the reference. This
1
2
9
10
8
3
4
11
5
–
+
–
+
–
+
–
+
EA
UVDET
OVDET
0.6V
7
0.65V
0.55V
–
+
0.35V
UV
OV
I
TH
SWITCHING
LOGIC
AND
BLANKING
CIRCUIT
S
R
Q
Q
RS
LATCH
BURST
–
+
I
COMP
I
RCMP
ANTI
SHOOT-
THRU
BURST
CLAMP
SLOPE
COMP
EN
SLEEP
POR
COUNTER
0.6V REF OSC
OSC
REGULATOR 2 (IDENTICAL TO REGULATOR 1)
PGOOD1
PGOOD2
34074 BD
SHUTDOWN
V
IN
V
IN
V
IN
6
REGULATOR 1
SW1
GND
POR
GND
SW2
5Ω
MODE/SYNC
V
FB1
RUN1
RUN2
V
FB2
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

LTC3407EDD-4#PBF

Mfr. #:
Buy LTC3407EDD-4#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Dual, Sync. 800mA, 2.25MHz Step-dwn Convrtr in DFN
Lifecycle:
New from this manufacturer.
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