LTC3785 Datasheet, PDF (7/20 Pages) Linear Technology – 10V, High Effi ciency, Synchronous, No RSENSE Buck-Boost Controller

LTC3785
BLOCK DIAGRA
V_IN
2.7V TO 10V
24
1.225V +
–
FAULT
LOGIC
TSD
1.225V
V_REF
V_IN
4.5V REG
–
V_{BE +}
RUN UVLO
C_SS
RUN/SS
1
1µA
2µA
2.4V
I_LIMIT
1/25k
IDEAL DIODE
g_m
V = 60k/R_ILSET
ADRV
100% DUTY
CHARGE PUMP
I_LIM(OUT)
I_LIM(OUT)
10µA MAX
–6.5% +
UV
V_OUT
–
V_OUT
V_SENSE
4
+10%
–
OV
+
R1
FB
3
R2
C_P1
V_C
2
1.225V
+
–
R_T
RT
7
OSC
I_MAX
SW1
PULSE
UV
BDRV
OV
SW2
PULSE
REVERSE
LIMIT
DDRV
V = 90k/R_ILSET
BBM TG1
SW1
DELAY BG1
X10
SAMPLED
BBM TG2
SW2
DELAY BG2
DISABLE
V_OUT
LOW
15mV
OR
1X I_LIMIT
REVERSE
V_REV
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
BURST
R_ILSET
I_LSET
5
SS
I_LIMIT
SET
I_LIM COMP
I_MAX COMP
1/2 LIMIT AT V_OUT < 1V
CDRV
GND/PGND
25
SAMPLED
V_DRV
V_REV
PGND
0 = 15mV
1 = I_LIMIT
V_CC
23
I_SVIN
22
TG1
20
V_BST1
21
SW1 ^CA
19
I_SSW1
18
V_DRV
16
BG1
17
I_SVOUT
10
TG2
12
V_BST2
11
SW2
13
I_{SSW2 14}
BG2
15
CCM
6
C_VCC
MA
C_IN
SW1
D1
OPT
MB
L1
D2
OPT
MD
V_OUT
C_B
SW2
MC
C_OUT
3785 BD
3785f
7