Datasheet

OUT
VCC
REF
GND
FB
COMP
CS
RC
1
2
3
4
8
7
6
5
COMP
FB
CS
RC
REF
VCC
OUT
GND
8
7
6
5
1
2
3
4
UCC2813-0, UCC2813-1, UCC2813-2, UCC2813-3, UCC2813-4, UCC2813-5
UCC3813-0, UCC3813-1, UCC3813-2, UCC3813-3, UCC3813-4, UCC3813-5
www.ti.com SLUS161D –APRIL 1999–REVISED JUNE 2013
DEVICE INFORMATION
DIL-8 (PDIP) OR SOIC-8 TSSOP-8
N (P) OR D PACKAGE PW PACKAGE
(TOP VIEW) (TOP VIEW)
PIN DESCRIPTIONS
COMP: COMP is the output of the error amplifier and the input of the PWM comparator.
Unlike other devices, the error amplifier in the UCC3813 family is a true low-output-impedance 2-MHz
operational amplifier. As such, the COMP terminal both sources and sinks current. However, the error amplifier is
internally current limited, so that zero duty cycle is commanded by externally forcing COMP to GND.
The UCC3813 family features built-in full cycle soft start. Soft start is implemented as a clamp on the maximum
COMP voltage.
CS: CS is the input to the current-sense comparators. The UCC3813 family has two different current-sense
comparators: the PWM comparator and an overcurrent comparator.
The UCC3813 family contains digital current-sense filtering, which disconnects the CS terminal from the current
sense comparator during the 100-ns interval immediately following the rising edge of the OUT pin. This digital
filtering, also called leading-edge blanking, means that in most applications, no analog filtering (RC filter) is
required on CS. Compared to an external RC filter technique, the leading-edge blanking provides a smaller
effective CS to OUT propagation delay. Note, however, that the minimum non-zero On-Time of the OUT signal is
directly affected by the leading-edge-blanking and the CS to OUT propagation delay.
The overcurrent comparator is only intended for fault sensing, and exceeding the overcurrent threshold causes a
soft start cycle.
FB: FB is the inverting input of the error amplifier. For best stability, keep FB lead length as short as possible
and FB stray capacitance as small as possible.
GND: GND is reference ground and power ground for all functions on this part.
OUT: OUT is the output of a high-current power driver capable of driving the gate of a power MOSFET with peak
currents exceeding ±750 mA. OUT is actively held low when VCC is below the UVLO threshold.
The high-current power driver consists of FET output devices, which can switch all of the way to GND and all of
the way to VCC. The output stage also provides a very low impedance to overshoot and undershoot which
means that in many cases, external schottky clamp diodes are not required.
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Product Folder Links: UCC2813-0 UCC2813-1 UCC2813-2 UCC2813-3 UCC2813-4 UCC2813-5 UCC3813-0
UCC3813-1 UCC3813-2 UCC3813-3 UCC3813-4 UCC3813-5