LTC3892_15 Datasheet, PDF (29/36 Pages) Linear Technology – 60V Low IQ, Dual, 2-Phase Synchronous Step-Down DC/DC Controller

Applications Information
LTC3892/LTC3892-1
V_IN
R_IN
C_IN
SW1
L1
R_{SENSE1 VOUT1}
C_OUT1
R_L1
SW2
BOLD LINES INDICATE
HIGH SWITCHING
CURRENT. KEEP LINES
TO A MINIMUM LENGTH.
L2
R_{SENSE2 VOUT2}
C_OUT2
R_L2
38921 F11
Figure 10. Branch Current Waveforms
3. Does the LTC3892/LTC3892-1 V_FB pin’s resistive divider
connect to the (+) terminal of C_OUT? The resistive divider
must be connected between the (+) terminal of C_OUT
and signal ground. The feedback resistor connections
should not be along the high current input feeds from
the input capacitor(s).
4. Are the SENSE^– and SENSE⁺ leads routed together with
minimum PC trace spacing? The filter capacitor between
SENSE⁺ and SENSE^– should be as close as possible
to the IC. Ensure accurate current sensing with Kelvin
connections at the SENSE resistor.
5. Is the DRV_CC and decoupling capacitor connected close
to the IC, between the DRV_CC and the ground pin? This
capacitor carries the MOSFET drivers’ current peaks.
6. Keep the switching nodes (SW1, SW2), top gate (TG1,
TG2), and boost nodes (BOOST1, BOOST2) away from
sensitive small-signal nodes, especially from the op-
posites channel’s voltage and current sensing feedback
pins. All of these nodes have very large and fast moving
signals and therefore should be kept on the output side
of the LTC3892/LTC3892-1 and occupy minimum PC
trace area.
7. Use a modified star ground technique: a low impedance,
large copper area central grounding point on the same
side of the PC board as the input and output capacitors
with tie-ins for the bottom of the DRV_CC decoupling
capacitor, the bottom of the voltage feedback resistive
divider and the GND pin of the IC.
For more information www.linear.com/LTC3892
38921f
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