MC33260
PIN FUNCTION DESCRIPTION
Pin No.
1
Function
Feedback Input
Description
This pin is designed to receive a current that is proportional to the preconverter output voltage. This
information is used for both the regulation and the overvoltage and undervoltage protections. The
current drawn by this pin is internally squared to be used as oscillator capacitor charge current.
This pin makes available the regulation block output. The capacitor connected between this pin and
ground, adjusts the control bandwidth. It is typically set below 20 Hz to obtain a nondistorted input
current.
The circuit uses an on–time control mode. This on–time is controlled by comparing the CT voltage to
the Vcontrol voltage. CT is charged by the squared feedback current.
This pin is designed to receive a negative voltage signal proportional to the current flowing through
the inductor. This information is generally built using a sense resistor. The Zero Current Detection
prevents any restart as long as the pin 4 voltage is below (–60 mV). This pin is also used to perform
the peak current limitation. The overcurrent threshold is programmed by the resistor connected
between the pin and the external current sense resistor.
This pin is designed to receive a synchronization signal. For instance, it enables to synchronize the
PFC preconverter to the associated SMPS. If not used, this pin must be grounded.
This pin must be connected to the preregulator ground.
The gate drive current capability is suited to drive an IGBT or a power MOSFET.
This pin is the positive supply of the IC. The circuit turns on when VCC becomes higher than 11 V, the
operating range after start–up being 8.5 V up to 16 V.
2
Vcontrol
3
4
Oscillator Capacitor
(CT)
Zero Current
Detection Input
5
6
7
8
Synchronization
Input
Ground
Gate Drive
VCC
APPLICATION SCHEMATIC
D1...D4
Filtering
Capacitor
L1
D1
+ C1
1
2
Vcontrol
3
4
ROCP
CT
MC33260
8
7
6
5
Sync
VCC
M1
Ro
Load
(SMPS, Lamp
Ballast,...)
Rcs
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8
ONSEMI [ ON SEMICONDUCTOR ]
