ISL6307A Datasheet, PDF (23/33 Pages) Intersil Corporation – Ultra-high bandwidth 6-Phase PWM Controller with 8 Bit VID Code Capable of Precision RDS(ON) or DCR Differential Current Sensing

OUTPUT CURRENT, 50A/DIV
0A
OUTPUT VOLTAGE,
500mV/DIV
ISL6307A
In normal operation, DRVEN remains low until ISL6307A
begins soft-start ramp and then is pulled high (Figure 14).
When an overcurrent event occurs, DRVEN is pulled low
instantly, less than 20ns, to disable the driver so that both
upper and lower FETs turn off (Figure 15). During an
overvoltage condition, DRVEN remains high to allow the
drivers to turn on the lower FETs to discharge the energy
stored in the output inductor. Once the output voltage is
reduced to 0.4V, DRVEN is pulled low, as shown in
Figure 16.
DRVEN, 5V/DIV
0V
2ms/DIV
FIGURE 13. OVERCURRENT BEHAVIOR IN HICCUP MODE.
F_SW = 500kHz
At the beginning of overcurrent shutdown, the controller
places all PWM signals in a high-impedance state within
20ns, commanding the Intersil MOSFET driver ICs to turn off
both upper and lower MOSFETs. The system remains in this
state for a period of 4096 switching cycles. If the controller is
still enabled at the end of this waiting period, it will attempt a
soft-start. If the fault remains, the trip-retry cycles will
continue indefinitely (as shown in Figure 13) until either the
controller is disabled or the fault is cleared. Note, the energy
delivered during trip-retry cycling is much less than during
full-load operation. There is no thermal hazards during this
kind of operation.
0V
OUTPUT CURRENT, 50A/DIV
0A
OUTPUT VOLTAGE,
500mV/DIV
0V
2ms/DIV
FIGURE 15. DRVEN DURING OVERCURRENT OPERATION
DRVEN, 5V/DIV
DRVEN, 5V/DIV
VOUT, 1V/DIV
EN, 5V/DIV
OUTPUT VOLTAGE,
500mV/DIV
500µs/DIV
FIGURE 14. DRVEN WAVEFORM AT STARTUP
Driver Enable Output
The ISL6307A has a driver enable output pin, DRVEN.
DRVEN is designed for applications where ISL6307A need
to work with drivers that can not recognize three-state PWM
input.
2ms/DIV
FIGURE 16. DRVEN DURING OVERVOLTAGE OPERATION
There’s no need to use DRVEN when ISL6307A is used with
Intersil’s 12V drivers, such as ISL6612 and ISL6614. For
drivers such as ISL6609 and ISL6605, DRVEN output of
ISL6307A can be connected to the EN pin of the driver.
23
FN9236.0
February 6, 2006