BD83732HFP-M_16 Datasheet, PDF (13/33 Pages) Rohm – 1ch Source Driver for Automotive

BD83732HFP-M / BD83733HFP-M
(4) Prevention of false LED Short Detection during PWM
When in Linear control mode, LED Open & Short Circuit Detection are active continuously.
In PWM Dimming mode, LED Open Detection is active only during the Fall time of VCRT, but LED Short Circuit Detection is
active at all time. (Refer to Figure20.)
When IOUT is disabled during PWM, the output will be high impedance ( ‘Hi-Z’). During this time noise ^(Note1) can couple on
to this pin and cause false detection of SHORT condition.
To prevent this it is necessary to connect a Capacitor(more than 0.1μF^(Note2)) between IOUT terminal and GND
terminal nearby terminal
(ROHM Recommended Value : CIOUT=0.1μF GCM188R11H104KA42 murata)
(Note1) Conducted noise, Radiated noise, Interference of connecter and PCB pattern etc…
(Note2) If more than 0.1μF, please evaluate the time of V_IN on to I_IOUT on. (See Page 14 evaluation example)
Linear Control Mode
VIN
0V
VCRT
0V
VIOUT
0V
IIOUT
0mA
IOUT Terminal
Hi-Z zone
LED Open
Detection
None
Active
PWM Dimming Mode
VIN
0V
VCRT
VIOUT
0V
IIOUT
0mA
IOUT Terminal
Hi-Z zone
LED Open
Detection
Hi-Z
Hi-Z
Hi-Z
Active
Active
Active
LED Short
Circuit
Detection
Active
LED Short
Circuit
Detection
Active
Figure 21. Timing of LED Open & Short Circuit Detection Function
and IOUT Terminal Hi-Z zone
PWM_in
DC_in
+B
D1
ZD1
D2
D3
RDCIN
RPBUS1
ZD2
RPBUS2
RTHM
RVIN_F
CVIN
CCRT RCRT
VIN_F
VIN
IOUT
CRT _BD83732HFP-M
BD83733HFP-M
DISC
FIN
PBUS
GND
CIOUT
Figure 22. About the capacitor of connecting IOUT terminal
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TSZ22111・15・001
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TSZ02201-0G1G0C700310-1-2
2016.Aug.25 Rev.003