MAX15034 Datasheet, PDF (21/25 Pages) Maxim Integrated Products – Configurable, Single-/Dual-Output, Synchronous Buck Controller for High-Current Applications

Configurable, Single-/Dual-Output, Synchronous
Buck Controller for High-Current Applications
L_OUT
R_SENSE
LX_
V_OUT
MAX15034
CSP_
CSN_
Figure 8. Noninductive Resistive Sense
LX_
MAX15034
INDUCTOR
L
DCR
V_OUT
R1
C1
CSP_
C2*
CSN_
Figure 9. Lossless Inductor Sense
Set the RC time constant to be 1.1 to 1.2 times the
inductor time constant (L/DCR). Select C1 to be in the
0.1μF to 0.47μF range, and then calculate R1 from:
R1[kΩ] = ^{1.2 × L[μH]}
DCR[mΩ] × C1[μF]
In some applications, it may be useful to add a resistor
(R2 in Figure 9) in series with the CSN_ connection to
minimize input offset error. Set R2 equal to R1. It may
also prove useful to add capacitor C3 (Figure 9) in
R2*
C3*
*OPTIONAL.
parallel with R2 to aid in short-circuit recovery. Set C3
equal to C1. Finally, it may be helpful to add a 100pF
(C2) capacitor immediately across the CSP_ and CSN_
inputs to minimize high-frequency noise pick-up at the
IC in some applications.
For current-sense resistors that have a noticeable
inductance component, use lossless inductor sense
implementation (and design procedure). See Figure 10.
Table 3 highlights the tradeoffs of each current-sense
method.
Table 3. Current-Sense Configurations
METHOD
Output Current-Sense Resistor
Equivalent Inductor DC Resistance
CURRENT-SENSE
ACCURACY
High
Low
INDUCTOR-SATURATION
PROTECTION
Allowed (highest accuracy)
Allowed
CURRENT-SENSE POWER
LOSS (EFFICIENCY)
R_SENSE x I_OUT2
No additional loss
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