Nxp Semiconductors SSL2102 Evaluation Boards SSL2102T/DB/FLYB120V,598 SSL2102T/DB/FLYB120V,598 Scheda Tecnica

SSL2102

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© NXP B.V. 2011. All rights reserved.

The SSL2102 IC contains some circuitry intended for mains dimmer compatibility. This 
circuit contains two current sinks that are called bleeders. A strong bleeder is used for 
zero-cross reset of the dimmer and TRIAC latching. A weak bleeder is added to maintain 
the hold current through the dimmer.

The strong bleeder switch is switched on when the maximum voltage on the WBLEED pin 
and the SBLEED pin is below the V

th(SBLEED)

 level (52 V typically). The weak bleeder 

switch is switched on as soon as the voltage on pin ISENSE exceeds the V

th(high)(ISENSE)

 

level (

100 mV typically). The weak bleeder switch is switched off when the ISENSE 

voltage drops below the V

th(low)(ISENSE)

 level (

250 mV typically). The weak bleeder switch 

is also switched off when the strong bleeder switch is switched on. See 

 

A new cycle is started when the primary switch is switched on (see 

). After a time 

determined by the oscillator voltage, RC and the internal regulation level, the switch is 
turned off and the secondary stroke starts. The internal regulation level is determined by 
the voltage on pin PWMLIMIT. 

After the secondary stroke, the drain voltage shows an oscillation with a frequency of 
approximately:

(2)

Where:

L

p

 = primary self inductance

C

p

 = parasitic capacitance on drain node

WBLEED

SBLEED

D2

D3

20 

μ

A

LOW V DETECT

Q

R

S

−

0.1 V

−

0.25 V

ISENSE

GND

M2

M1

I1

Integrated

B1

OR













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