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LTC3785-1 Datasheet, PDF (7/20 Pages) Linear Technology – 10V, High Effi ciency, Buck-Boost Controller with Power Good
LTC3785-1
BLOCK DIAGRAM
VIN
2.7V TO 10V
24
1.225V +
–
FAULT
LOGIC
TSD
1.225V
VREF
VIN
4.5V REG
CSS
RUN/SS
1
–
VBE +
1μA
RUN UVLO
2μA
2.4V
ILIMIT
1/25k
IDEAL DIODE
gm
V = 60k/RILSET
ADRV
100% DUTY
CHARGE PUMP
ILIM(OUT)
ILIM(OUT)
10μA MAX
VOUT
–7.5% +
UV
–
VOUT
VSENSE
4
7.5%
–
OV
+
R1
FB
3
R2
CP1
VC
2
1.225V
+
–
RT
RT
7
OSC
IMAX
SW1
PULSE
UV
BDRV
OV
SW2
PULSE
REVERSE
LIMIT
DDRV
V = 90k/RILSET
BBM TG1
SW1
DELAY BG1
X10
SAMPLED
BBM TG2
SW2
DELAY BG2
DISABLE
VOUT
LOW
15mV
OR
1X ILIMIT
REVERSE
VREV
CURRENT LIMIT
(ZERO LIMIT FOR BURST)
1.8V
PGND
100% DUTY
CHARGE PUMP
1.5V
MODE
8
1 = Burst Mode OPERATION
– 0 = FIXED FREQUENCY
+
BURST
LOGIC
RILSET
ILSET
5
SS
ILIMIT
SET
ILIM COMP
IMAX COMP
1/2 LIMIT AT VOUT < 1V
UV
OV
SD
UVLO
BURST
CDRV
PGOOD
9
GND/PGND
25
SAMPLED
VDRV
VREV
PGND
0 = 15mV
1 = ILIMIT
VCC
23
ISVIN
22
TG1
20
VBST1
21
SW1 CA
19
ISSW1
18
VDRV
16
BG1
17
ISVOUT
10
TG2
12
VBST2
11
SW2
13
ISSW2
14
BG2
15
CCM
6
CVCC
MA
CIN
SW1
D1
OPT
MB
L1
D2
OPT
MD
VOUT
CB
SW2
MC
COUT
37851 BD
37851f
7