LTC3731 Datasheet, PDF (9/32 Pages) Linear Technology – 3-Phase, 600kHz, Synchronous Buck Switching Regulator Controller

W
FU CTIO AL DIAGRA
PLLIN
F_IN
50k
R_LP ^PLLFLTR
C_LP
CLKOUT
PHASMD**
PHASE DET
OSCILLATOR
CLK1
CLK2
CLK3
LTC3731
PGOOD**
100µs
DELAY
PROTECTION
FCB
+
–
0.6V
IN^–
40k
IN⁺
40k
DIFFOUT
0.66V
EAIN
0.54V
FCB
40k
–
A1
+
40k
R1
EAIN
V_FB
R2
0.600V
0.660V
I_TH
–
EA
+
OV
+
–
C_C
R_C
UVADJ
–
1.2V +
DUPLICATE FOR SECOND AND THIRD
CONTROLLER CHANNELS
BOOST
RS
LATCH
DROP
OUT
DET
BOT
TG
TOP
SQ
FORCE BOT
RQ
SWITCH
SW
LOGIC
0.55V
B
FCB
SHDN
V_CC (VDR)***
BG
BOT
PGND
V_CC
V_IN
D_B
C_B
+
C_IN
I₁ – +
SLOPE
COMP
5(V_FB)
0.86V
SS
CLAMP _2.4V
3mV
54k
–
I₂
+
54k
L
V_CC
36k ^SENSE+
36k ^SENSE–
R_SENSE
C_OUT
V_OUT
FCB
V_CC
1.5µA
6V
SHDN
RST
5(V_FB)
SHED
RUN
SOFT-
START
1.2V
0.600V
INTERNAL
SUPPLY
UV RESET
V_REF
V_CC
SGND*
V_CC
+
C_CC
RUN/SS
C_SS
*THE LTC3731CUH USES THE EXPOSED DIE ATTACH PAD FOR THE SGND CONNECTIONS
**THE PHASMD AND PGOOD PIN FUNCTIONS ARE TIED TOGETHER IN THE LTC3731CUH PACKAGE
***LTC3731CG/HG ONLY
Figure 2
3731 F02
3731fa
9