MAX5071 Maxim Integrated Products, MAX5071 Datasheet - Page 12

• Manufacturer Part Number: MAX5071
• Description: (MAX5070 / MAX5071) Current-Mode PWM Controllers
• Manufacturer: Maxim Integrated Products

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The advantages of current-mode control over voltage-
mode control are twofold. First, there is the feed-forward
characteristic brought on by the controller’s ability to
adjust for variations in the input voltage on a cycle-by-
cycle basis. Secondly, the stability requirements of the
current-mode controller are reduced to that of a single-
pole system unlike the double pole in the voltage-mode
control scheme.
High-Performance, Single-Ended, Current-Mode
PWM Controllers
Figure 2. MAX5071A/MAX5071B Functional Diagram
12
______________________________________________________________________________________
MAX5071A/MAX5071B
COMP
SYNC
GND
CS
3
5
1
2
Current-Mode Control Loop
BIDIRECTIONAL
SYNC
2R
1V
EN-DRV-BAR
ILIM
R
CPWM
1V
DELAY
REFERENCE
2.5V
2.5V
2.5V
REG_OK
The MAX5070/MAX5071 use a current-mode control loop
where the output of the error amplifier is compared to the
current-sense voltage (V
nal is lower than the noninverting input of the PWM com-
parator, the output of the CPWM comparator is low and
the switch is turned on at each clock pulse. When the
current-sense signal is higher than the inverting input of
the CPWM, the output of the CPWM comparator is high
and the switch is turned off.
OSC Q
PREREGULATOR
VP
5V
CLK
100% MAX DUTY CYCLE (MAX5071A)
50% MAX DUTY CYCLE (MAX5071B)
SHUTDOWN
THERMAL
S
R
Q
EN-REF
BG
SNS
VP
UVLO
CS
5V REGULATOR
VOLTAGE-
DIVIDER
). When the current-sense sig-
16V/10V
V
DD
VOLTAGE-
DIVIDER
26.5V
7
8
6 OUT
4 R
V
VREF
CC
T
/C
T