Rainbow Electronics MAX5974D - Manual (Page 12)

MAX5974A/MAX5974B/MAX5974C/MAX5974D
Active-Clamped, Spread-Spectrum,
Current-Mode PWM Controllers
12
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 cur-
rent 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 trans-
former for synchronous flyback application.
13 IN
Converter Supply Input. IN has wide UVLO hysteresis, enabling the design of efficient power sup-
plies. When the enable input EN is used to program a UVLO level for the power source, connect a
zener diode between IN and PGND to ensure that V
IN is always clamped below its absolute maxi-
mum rating of 26V.
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.