LTC1708-PG_15 Datasheet, PDF (9/32 Pages) Linear Technology – Dual Adjustable 5-Bit VID High Efficiency, 2-Phase Current Mode Synchronous Buck DC/DC Controller

LTC1708-PG
PI FU CTIO S
BOOST1, BOOST2 (Pins 33, 26): Bootstrapped Supplies
to the Topside Floating Drivers. Capacitors are connected
between the boost and switch pins and Schottky diodes
are tied between the boost and INTV_CC pins. Voltage swing
at the boost pins is from INTV_CC to (V_IN + INTV_CC).
SW1, SW2 (Pins 34, 25): Switch Node Connections to
Inductors. Voltage swing at these pins is from a Schottky
diode (external) voltage drop below ground to V_IN.
TG1, TG2 (Pins 35, 24): High Current Gate Drives for Top
N-Channel MOSFETs. These are the outputs of floating
drivers with a voltage swing equal to INTV_CC – 0.5V
superimposed on the switch node voltage SW.
PGOOD (Pin 36): Open-Drain Logic Output. PGOOD is
pulled to ground when the voltage at either EAIN pin is not
within 7.5% of the setpoint.
W
FU CTIO AL DIAGRA
FREQSET
1M
OSCILLATOR
PGOOD
1.19V
CLK1
CLK2
0.86V
V_FB1
0.74V
0.86V
DUPLICATE FOR SECOND
CONTROLLER CHANNEL
SQ
RQ
DROP
OUT
DET
BOOST
BOT FCB
TOP ON
TG
TOP
SW
SWITCH
LOGIC
INTV_CC
BG
BOT
V_SEC
0.17µA
FCB
3.3V_OUT
4.5V –
+
+
–
0.8V
V_FB2
0.74V
BINH
FCB
V_REF
V_IN
V_IN
EXTV_CC
INTV_CC
5V
+
SGND
4.8V +
–
STBYMD
ATTNIN
5V
LDO
REG
INTERNAL
SUPPLY
1.2µA
6V
0.6V +
–
SHDN
PGND
I₁
– ^I2
– ++ –
+
0.86V
3mV
4(V_FB)
SLOPE
COMP
45k
45k
2.4V
EA
OV
INTV_CC
30k ^SENSE+
30k ^SENSE–
V_FB
0.800V
EAIN
0.860V
I_TH
SHDN
RST
4(V_FB)
RUN
SOFT-
START
RUN/SS
R2
ATTNOUT _10k
5-BIT VID DECODER
R1
VARIABLE
40k
EACH VID
INPUT
INTV_CC
V_IN
D_B
C_B
+
D₁
R_SENSE
D_SEC
C_C
C_C2 RC
C_SS
C_IN
C_OUT
C_SEC
V_OUT
VID0 VID1 VID2 VID3 VID4
VIDV_CC
Figure 2
1708 F02
1708f
9