Rainbow Electronics MAX1585 - Manual (Page 16)

MAX1584/MAX1585
5-Channel Slim DSC Power Supplies
16 ______________________________________________________________________________________
OSC cycles, then all MAX1584/MAX1585 channels latch
off.
Maximum Duty Cycle
The MAX1584/MAX1585 auxiliary PWM controllers have
a guaranteed maximum duty cycle of 80%. In boost
designs that employ continuous current, the maximum
duty cycle limits the boost ratio so that:
1 - V IN / V OUT
≤ 80%
With discontinuous inductor current, no such limit exists
for the input/output ratio since the inductor has time to
fully discharge before the next cycle begins.
AUX1
AUX1 can be used for conventional DC-DC boost and
flyback designs (Figure 5). Its output (DL1) is designed
FB_
CC_
LEVEL
SHIFT
REF
0.85
REF
OSC
FAULT
PROTECTION
Q
CLK
DL_
MAX1584 AUX1 AND
AUX2, MAX1585 AUX1
STEP-UP CONTROLLER
ENABLE
REFI
SOFT-START
(REFI RAMPS FROM
0V TO REF IN 1024 OSC
CYCLES)
R
FB2
CC2
LEVEL
SHIFT
REF
0.85
REF
OSC
FAULT
PROTECTION
S
Q
CLK
DL2
MAX1585 AUX2
INVERTING CONTROLLER
ENABLE
REFI
SOFT-START
(REFI RAMPS FROM
REF TO 0V IN 1024 OSC
CYCLES)
R
S
FB3
CC3
LEVEL
SHIFT
REF
0.85
REF
OSC
FAULT
PROTECTION
Q
CLK
DL3
MAX1584 AND MAX1585
AUX3 STEP-DOWN
CONTROLLER
ENABLE
REFI
SOFT-START
(REFI RAMPS FROM
0V TO REF IN 1024 OSC
CYCLES)
R
S
Figure 3. AUX Controller Functional Diagrams