Advanced Feedback Dimming Ballast Control IC - Fairchild
Description
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fairchildsemi.
com
KA7543
Advanced Feedback Dimming Ballast Control IC
Features
• • • • • • • • • • • • • Lamp Current Feedback Soft Start on Feedback Voltage Dimming (0V~2V) on Feedback Switch off Control (Vdm=5V) Soft Dimming Control No Lamp Protection One Lamp Detection for Feedback Abnormal Protection Low Start-up and Operating Supply Current UVLO with 1.
8V Hysteresis Totem Pole Output Trimmed 1.
5% Internal Bandgap Reference 14-DIP & 14-SOP
Descriptions
The KA7543 is an advanced lamp current feedback dimming control IC.
This ballast control IC provides all of the necessary features to implement wide range dimming control, soft start and constant power consumption for intelligent electronic ballast systems.
The KA7543 is optimized for advanced electronic ballast systems requiring minimum board area.
External component counts can be reduced by adopting the KA7543.
Current feedback control method of the inverter status is one of the most attractive merits in KA7543.
Internal soft start circuitry eliminates the need for external soft start discrete components.
Voltage controlled soft dimming circuit is built into the IC to control the lighting output in a wide range.
Protection circuitry, no lamp protection, abnormal protection, one lamp detection, UVLO, restart on lamp adding , have been added.
14-DIP
Applications
• Electronic Ballast • Lighting Control System • Half Bridge Drive Control System
1
14-SOP
1
Rev.
1.
0.
3
©2002 Fairchild Semiconductor Corporation
KA7543
Internal Block Diagram
Output stage
OUT1
1
14
OUT2
Frequency divider
Protection reset +
NC
2 Reset Cs UVLO 9.
5V + sw 2V Vref (bandgap) 2V Internal bias bias 7V 1.
8V 7V Vz Supply Q Q + + 2V + R S + 4V Limiter -
0.
7V -
13
NC
ict 55pF 8ict 12
Vcc
3
GND
sw Oscillator + 1V
Cc
4 5.
7V Dimming starter 4V + 2V 5V regulator +
11
Cdm
11µA 5.
7V Mirror + isr 5V Switch + id 1/2 Mirror idr + + is-id Selecter 20kΩ + 3V + 1V 5pF 8 Dimmer 2V 9 20kΩ Gm + Soft starter 2V 10
V5
5 5/2 is
C...
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