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| MAX15034 Datasheet, PDF (15/25 Pages) Maxim Integrated Products – Configurable, Single-/Dual-Output, Synchronous Buck Controller for High-Current Applications | |||
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Configurable, Single-/Dual-Output, Synchronous
Buck Controller for High-Current Applications
VDD
CLP_
CSP_
CSN_
GMIN
AV = 36V/V
gm = 500μS
PWM
COMPARATOR
RAMP
CLK
2 x fSW (V/S)
1.225V
EN_
Figure 3. Current Comparator and MOSFET Driver Logic
S
Q
R
Q
BST_
DH_
LX_
DL_
PGND
VOUT
RF
R1
COUT
LOAD
EAN_
R2
VREF = 0.61V
Figure 4. Voltage Error Amplifier
EAOUT_
VCNTR + ÎVOUT/2
VCNTR
VCNTR - ÎVOUT/2
NO LOAD
1/2 LOAD
LOAD (A)
FULL LOAD
Figure 5. Defining the Voltage-Positioning Window
MOSFET Gate Drivers (DH_, DL_)
The high-side drivers (DH1 and DH2) and low-side dri-
vers (DL1 and DL2) drive the gates of external n-channel
MOSFETs. The high-peak sink and source current capa-
bility of these drivers provides ample drive for the fast
rise and fall times of the switching MOSFETs. Faster rise
and fall times result in reduced switching losses. For low-
output, voltage-regulating applications where the duty
cycle is less than 50%, choose high-side MOSFETs (Q2
and Q4, Figure 6) with a moderate RDS(ON) and a very
low gate charge. Choose low-side MOSFETs (Q1 and
Q3, Figure 6) with very low RDS(ON) and moderate gate
charge. The driver block also includes a logic circuit that
provides an adaptive nonoverlap time (30ns typ) to pre-
vent shoot-through currents during transition. Figure 7
shows the dual-phase, single-output buck regulator.
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