Rainbow Electronics MAX15034 - Manual (Page 21)

MAX15034
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:
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
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.
R k
L H
DCR m C F
1
1 2
1
[ ]
. [ ]
[ ] [ ]
Ω
Ω
=
Ч
Ч
μ
μ
Configurable, Single-/Dual-Output, Synchronous
Buck Controller for High-Current Applications
______________________________________________________________________________________ 21
L OUT R
SENSE
V
OUT LX_
CSP_
MAX15034
CSN_
Figure 8. Noninductive Resistive Sense
L
INDUCTOR
DCR
V OUT LX_
CSP_
MAX15034
CSN_
C2*
R1 C1
C3*
*OPTIONAL.
R2*
Figure 9. Lossless Inductor Sense
Table 3. Current-Sense Configurations
METHOD
CURRENT-SENSE
ACCURACY
INDUCTOR-SATURATION
PROTECTION
CURRENT-SENSE POWER
LOSS (EFFICIENCY)
Output Current-Sense Resistor High Allowed (highest accuracy) R SENSE x I OUT
2
Equivalent Inductor DC Resistance Low Allowed No additional loss