TDA4605D View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
TDA4605D Datasheet PDF : 7 Pages
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TDA4605
PIN CONFIGURATION
Pin
Number
1
2
3
4
5
6
7
8
Description
Regulating voltage : information input concerning secondary voltage.
By comparing the regulating voltage obtained from the regulating winding of the transformer with the
internal reference voltage, the output pulse width on Pin 5 is adapted to the load of the secondary side
(normal, overload, short circuit, no load)
Primary current simulation : information input regarding the primary current. The primary current rise in the
primary winding is simulated at Pin 2 as a voltage rise by means of external RC element. When a value is
reached that is derived from the regulating voltage at Pin 1, the output pulse at Pin 5 is terminated. The RC
element serves to set the maximum power at the overload point.
Primary voltage detector : input for primary voltage monitoring. When the line voltage is too low the IC is
switched-off by comparing V3 with an internal reference. Voltage at Pin 3 is used for overload point
compensation.
Ground
Output : push-pull output for charge and discharge of the gate capacitance of the power MOS transistor.
Supply voltage : Supply voltage input. From it are derived a stable internal reference voltage (VREF) and the
switching threshold V6A, V6E, V6 max and V6 min for the supply voltage detector.
if V6 > V6E the VREF is switched on and switched off when V6 < V6A. In addition the logic is only enable for
V6 min < V6 < V6 max.
Soft-start : input for soft-start and integration network. Start-up will begin with short pulses by connecting a
capacitor between Pin 7 to ground. This capacitor together with a resistor connected between Pin 7 and
error amplifier output also as acts an integrator network for regulation.
Zero detector : Input for the oscillator feedback. After starting oscillator, every zero transit of the feedback
voltage (falling edge) triggers an output pulse at Pin 5. The trigger threshold is at typically - 50mV
Figure 2. Block Diagram
TDA4605
Reference
Voltage
(typ. 3V)
6
Supply
Voltage
Monitor
2
V2B
Primary
Current
Recopy
5
Output Stage
and
Current Limit
VREF
Starting
4
V6min V6A V6E V6max
Vst
Impulse
Generator
Current
Source
Regulating
VR
& Overload
1
Amplifier
Stop
Comp.
Overload
Point
Vu
Correction
3
Low Voltage
Protection
Monitoring
7
Logic
Zero
Crossing
Detector
8
2/7
1
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