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11

IRPLMB1E

9. Design Tip: Auto-restart Option

The design can be modified to include re-lamp/auto-

restart option as shown in Fig. 9.1.

The resistors Rsupply must be moved across the

upper lamp filament and the lamp connected to the

bus voltage, instead than to ground. When the lamp

1

2

3

4

VCC

COM

VCO

LO

VS

HO

VB

8

7

6

5

FMIN

MHS

CBS

CVCC

RFMIN

F1

CBUS

RSUPPLY

DCP2

DCP1

LRES

CRES

CSNUB

CVCO

BR1

LF

CF

MLS

CDC

LAMP

Fig. 9.1: Circuit Modification to include auto-restart option

is replaced, Rsupply together with the upper filament

of the lamp provide a path from the DC bus to supply

the micro-power current to the IR2520 and to restart

the IR2520 as soon as VCC exceeds the UVLO+

threshold. Rsupply need to be able to handle high

voltage. If using SMD components, 2 resistors are

needed.