TOP242R POWERINT [Power Integrations, Inc.], TOP242R Datasheet - Page 10

• Manufacturer Part Number: TOP242R
• Description: TOPSwitch -GX Family Extended Power, Design Flexible, EcoSmart, Integrated Off-line Switcher
• Manufacturer: POWERINT [Power Integrations, Inc.]

is also used to generate a temperature-compensated current
reference which is trimmed to accurately set the switching
frequency, MOSFET gate drive current, current limit, and the
line OV/UV thresholds. TOPSwitch-GX has improved circuitry
to maintain all of the above critical parameters within very tight
absolute and temperature tolerances.
High-Voltage Bias Current Source
This current source biases TOPSwitch-GX from the DRAIN
pin and charges the CONTROL pin external capacitance
10
TOP242-250
G
1/02
during start-up or hysteretic operation. Hysteretic operation
occurs during auto-restart, remote off and over-temperature
shutdown. In this mode of operation, the current source is
switched on and off with an effective duty cycle of approxi-
mately 35%. This duty cycle is determined by the ratio of
CONTROL pin charge (I
I
operation when the output MOSFET is switching. The effect
of the current source switching will be seen on the DRAIN
voltage waveform as small disturbances and is normal.
CD2
). This current source is turned off during normal
C
) and discharge currents (I
CD1
and