UCC2817, UCC2818, UCC3817, UCC3818

BiCMOS POWER FACTOR PREREGULATOR

SLUS395J - FEBRUARY 2000 - REVISED MARCH 2009

5

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PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

VFF output current

IAC = 300 µA

−140

−150

−160

µA

soft start section

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

SS charge current

−6

−10

−16

µA

gate driver section

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

Pullup resistance

IO = –100 mA to −200 mA

5

12

Ω

Pulldown resistance

IO = 100 mA

2

10

Ω

Output rise time

CL = 1 nF,

RL = 10 Ω,

VDRVOUT = 0.7 V to 9.0 V

25

50

ns

Output fall time

CL = 1 nF,

RL = 10 Ω,

VDRVOUT = 9.0 V to 0.7 V

10

50

ns

Maximum duty cycle

93

95

99

%

Minimum controlled duty cycle

At 100 kHz

2

%

zero power section

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

Zero power comparator threshold

Measured on VAOUT

0.20

0.33

0.50

V

pin descriptions

CAI: (current amplifier noninverting input) Place a resistor between this pin and the GND side of current sense

resistor. This input and the inverting input (MOUT) remain functional down to and below GND.

CAOUT: (current amplifier output) This is the output of a wide bandwidth operational amplifier that senses line

current and commands the PFC pulse-width modulator (PWM) to force the correct duty cycle. Compensation

components are placed between CAOUT and MOUT.

CT: (oscillator timing capacitor) A capacitor from CT to GND sets the PWM oscillator frequency according to:

f

[

0.6

RT

CT

The lead from the oscillator timing capacitor to GND should be as short and direct as possible.

DRVOUT: (gate drive) The output drive for the boost switch is a totem-pole MOSFET gate driver on DRVOUT.

Use a series gate resistor to prevent interaction between the gate impedance and the output driver that might

cause the DRVOUT to overshoot excessively. See characteristic curve (Figure 13) to determine minimum

required gate resister value. Some overshoot of the DRVOUT output is always expected when driving a

capacitive load.

GND: (ground) All voltages measured with respect to ground. VCC and REF should be bypassed directly to

GND with a 0.1-

µF or larger ceramic capacitor.