Datasheet
13Maxim Integrated
Active-Clamped, Spread-Spectrum,
Current-Mode PWM Controllers
MAX5974A/MAX5974B/MAX5974C/MAX5974D
Pin Description (continued)
PIN NAME FUNCTION
6 FB Transconductance Amplifier Inverting Input
7 GND Signal Ground
8 CSSC
Current Sense with Slope Compensation Input. A resistor connected from CSSC to CS programs the
amount of slope compensation. See the Programmable Slope Compensation section.
9 CS
Current-Sense Input. Current-sense connection for average current sense and cycle-by-cycle
current limit. Peak current-limit trip voltage is 400mV and reverse current-limit trip voltage is -100mV.
10 PGND Power Ground. PGND is the return path for gate-driver switching currents.
11 NDRV Main Switch Gate-Driver Output
12 AUXDRV
pMOS Active Clamp Switch Gate-Driver Output. AUXDRV can also be used to drive a pulse
transformer for synchronous flyback application.
13 IN
Converter Supply Input. IN has wide UVLO hysteresis, enabling the design of efficient power
supplies. See the Enable Input section to determine if an external zener diode is required at IN.
14 EN
Enable Input. The gate drivers are disabled and the device is in a low-power UVLO mode when the
voltage on EN is below V
ENF
. When the voltage on EN is above V
ENR
, the device checks for other
enable conditions. See the Enable Input section for more information about interfacing to EN.
15 DCLMP
Feed-Forward Maximum Duty-Cycle Clamp Programming Input. Connect a resistive divider between
the input supply voltage DCLMP and GND. The voltage at DCLMP sets the maximum duty cycle
(D
MAX
) of the converter inversely proportional to the input supply voltage, so that the MOSFET
remains protected during line transients.
16 SS
Soft-Start Programming Capacitor Connection. Connect a capacitor from SS to GND to program the
soft-start period. This capacitor also determines hiccup mode current-limit restart time. A resistor
from SS to GND can also be used to set the D
MAX
below 75%.
— EP
Exposed Pad. Internally connected to GND. Connect to a large ground plane to maximize thermal
performance. Not intended as an electrical connection point.