LTC3826-1 Datasheet, PDF (25/32 Pages) Linear Technology – 30μA IQ, Dual, 2-Phase Synchronous Step-Down Controller

LTC3826-1
APPLICATIONS INFORMATION
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 INTV_CC decoupling capacitor connected close to
the IC, between the INTV_CC and the power ground pins?
This capacitor carries the MOSFET drivers current peaks.
An additional 1μF ceramic capacitor placed immediately
next to the INTV_CC and PGND pins can help improve
noise performance substantially.
6. Keep the switching nodes (SW1, SW2), top gate nodes
(TG1, TG2), and boost nodes (BOOST1, BOOST2) away
from sensitive small-signal nodes, especially from
the opposites 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 LTC3826-1 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
INTV_CC decoupling capacitor, the bottom of the voltage
feedback resistive divider and the SGND pin of the IC.
V_IN
R_IN
C_IN
SW1
D1
L1
R_{SENSE1 VOUT1}
C_OUT1
BOLD LINES INDICATE
HIGH SWITCHING
CURRENT. KEEP LINES
TO A MINIMUM LENGTH.
SW2
D2
L2
R_{SENSE2 VOUT2}
C_OUT2
Figure 12. Branch Current Waveforms
R_L1
R_L2
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