Block Diagram Of Mc44603; Pin Function Description - Philips DVD 950 Service Manual

Current mode power supply 30PS203
10.4 Blockdiagram of MC44603
MC44603P
DEMAGNETISATION
DETECT
8 DEMAGNETISATION
MANAGEMENT
Iref
9
SYNC INPUT
OSCILLATOR
10
CT
15
RF STANDBY
Vstby
12 STANDBY
RP STANDBY
(REDUCED FREQUENCY)
2.5V
VOLTAGE ERROR
AMP
14
FEEDBACK
13
E/A OUT
FOLDBACK
FOLDBACK
INPUT
5

10.5 Pin function description

Pin function description
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Vref
REFERENCE
BLOCK
VOSC PROT
VOSC
VS8 OUT
CURRENT
SENSE
CURRENT SENSE
INPUT
7
Name Description
VCC This pin is the positive supply of the IC. The operating voltage range after start-up is 9.0 to 14.5 V.
VC The output high state (VOH) is set by the voltage applied to this pin.
Output Peak currents up to 750 mA can be sourced or sunk, suitable for driving either MOSFET or Bipolar transistors.
Gnd The groundpin is a single return, typically connected back to the power source.
Foldback Input The foldback function provides overload protection.
Overvoltage When the overvoltage protection pin receives a voltage greater than 2.5V, the device is disabled and requires a
Protection complete restart sequence.
Current Sense A voltage proportional to the current flowing into the power switch is connected to this input.
Input
Demagnetisation A voltage delivered by an auxiliary transformer winding provides to the demagnetisation pin an indication of the
Detection magnetisation state of the flyback transformer. A zero voltage detection corresponds to complete core
saturation.
Synchronisation The synchronisation input pin can be activated with either a negative pulse going from a level between 0.7V and
Input 3.7V to Gnd or a positive pulse going from a level between 0.7V and 3.7V up to a level higher than 3.7V. The
oscillator runs free when Pin 9 is connected to Gnd.
C The normal mode oscillator frequency is programmed by the capacitor CT choice together with the Rref
T
resistance value. CT, connected between Pin 10 and Gnd, generates the oscillator sawtooth.
Soft- A capacitor, resistor or a voltage source connected to this pin limits the switching duty-cycle. This pin can be
Start/Dmax/Volta used as a voltage mode control input. By connecting Pin 11 to Ground, the MC44603 can be shut down.
ge-Mode
RP Standby A voltage level applied to the RP Standby pin determines the output power level at which the oscillator will turn
into the reduced frequency mode of operation(i.e. standby mode). An internal hysteresis comparator allows to
return in the normal mode at a higher output power level.
E/A Out The error amplifier output is made available for loop compensation.
Voltage This is the inverting input of the Error Amplifier. It can be connected to the switching power supply output
Feedback through an optical (or other) feedback loop.
RF Standby The reduced frequency or standby frequency programming is made by the RF Standby resistance choice.
Iref
Vref
enable
SUPPLY
INITIALISATION BLOCK
1Set
LATCH
C
=1 1Reset
THERMAL
SHUTDOWN
Dmax &
SOFT-START
CONTROL
SOFT-START
& DMAX
11
Figure 10-3
Figure 10-4
DVD 950
1
UVL01
BUFFER
Vref
Iref
OVER
UVL01
VOLTAGE
MANAGEMENT
Vref
10. GB 57
2
VC
3
OUT
4
GND
Voc
OVER
VOLTAGE
PROTECT
6
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