LTC3703_15 Datasheet, PDF (29/34 Pages) Linear Technology – 100V Synchronous Switching Regulator Controller

LTC3703
Applications Information
5. Place the small-signal components away from high
frequency switching nodes (BOOST, SW, TG, and BG).
In the layout shown in Figure 20, all the small-signal
components have been placed on one side of the IC
and all of the power components have been placed on
the other. This also helps keep the signal ground and
power ground isolated.
6. A separate decoupling capacitor for the supply, V_CC,
is useful with an RC filter between the DRV_CC supply
and V_CC pin to filter any noise injected by the drivers.
Connect this capacitor close to the IC, between the
V_CC and GND pins and keep the ground side of the V_CC
capacitor (signal ground) isolated from the ground side
of the DRV_CC capacitor (power ground).
7. For optimum load regulation and true remote sensing,
the top of the output resistor divider should connect
independently to the top of the output capacitor (Kelvin
connection), staying away from any high dV/dt traces.
Place the divider resistors near the LTC3703 in order
to keep the high impedance FB node short.
8. For applications with multiple switching power con-
verters connected to the same input supply, make
sure that the input filter capacitor for the LTC3703
is not shared with other converters. AC input current
from another converter could cause substantial input
voltage ripple, and this could interfere with the opera-
tion of the LTC3703. A few inches of PC trace or wire
(L ≅ 100nH) between C_IN of the LTC3703 and the actual
source V_IN should be sufficient to prevent input noise
interference problems.
V_CC
V_IN
R_C1
C_C2
R2
R_C2 R1
C_C3
1 _{MODE/SYNC VIN} 16
R_{SET 2 fSET}
BOOST ¹⁵
3
LTC3703
COMP
TG ¹⁴
C_C1
4 _FB
SW ¹³
R_{MAX 5 IMAX}
VCC ¹²
6 _INV
C_SS
7 _RUN/SS
DRV_CC ¹¹
BG ¹⁰
8 _GND
BGRTN ⁹
C_VCC
X5R
D_B
M1
C_B
R_F
M2
C_DRVCC
X5R
+
C_IN
L1
+
C_OUT
D1
+
V_OUT
–
3703 F18
Figure 20. LTC3703 Buck Converter Suggested Layout
3703fc
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