Datasheet

1
2
3
4
5
6
7
8
GD1
VCC
GND
GD2
DT
RT
OC
SS
UCC25600
www.ti.com SLUS846B –SEPTEMBER 2008– REVISED JULY 2011
DEVICE INFORMATION
8-Pin SOIC, Top View
TERMINAL FUNCTIONS
TERMINAL
DESCRIPTION
NAME NO. I/O
This pin sets the dead time of high-side and low-side switch driving signals. Connect
a resistor to ground. With internal 2.25-V voltage reference, the current flowing
DT 1 I through the resistor sets the dead time. To prevent shoot through when this pin is
accidentally short to ground, the minimum dead time is set to 120 ns. Any dead time
setting less than 120 ns will automatically have 120-ns dead time.
The current flowing out of this pin sets the frequency of the gate driver signals.
Connect the opto-coupler collector to this pin to control the switching frequency for
regulation purpose. Parallel a resistor to ground to set the minimum current flowing
RT 2 I out of the pin and set the minimum switching frequency. To set the maximum
switching frequency limiting, simply series a resistor with the opto-coupler transistor.
This resistor sets the maximum current flowing out of the pin and limits the maximum
switching frequency.
Over-current protection pin. When the voltage on this pin is above 1 V, gate driver
signals are actively pulled low. After the voltage falls below 0.6 V, the gate driver
OC 3 I
signal recovers with soft start. When OC pin voltage is above 2 V, the device is
latched off. Bringing VCC below UVLO level resets the overcurrent latch off.
Soft-start pin. This pin sets the soft-start time of the system. Connect a capacitor to
ground. Pulling this pin below 1 V will disable the device to allow easy ON/OFF
SS 4 I
control. The soft-start function is enabled after all fault conditions, including bias
supply OV, UVLO, over-current protection and over-temperature protection.
GD1 8 O
High-side and low-side switch gate driver. Connect gate driver transformer primary
side to these two pins to drive the half bridge.
GD2 5 O
GND 6 - Ground.
Bias Supply. Connect this pin to a power supply less than 20 V. Parallel a 1-μF
VCC 7 -
capacitor to ground to filter out noise.
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