BD9422EFV Datasheet, PDF (15/28 Pages) Rohm – White LED Driver for large LCD panel

BD9422EFV
●3.4 Connecting operation of Master/ slave
Master IC
SUMPWM
100k
SUMPWMDET
+
-
CS
Master:Low
RCS
Slave :High
MSDET
+
-
3V
Datasheet
PWM1
～
PWM6
A5V
+
-
ERRAMP
100k
FB
Master:ON
Slave :OFF
Re_スco_レg_ーn_ブiz_モe_ーd_ドs_認la_識ve mode
↓↓
エCラuーr アerンrプorシaンmクp側sカinットk side
マス^Rタ^eー^cモ^ogーⁿドⁱ認^ze識^{d master mode}
かつ and even one of slave’s
スレーブ側のみPWM on
どれか1つでもPWMが_↓ON
↓
プルア^Aッ^dプ^d付^p加^{ull-up resistance}
Recognized master mode
マスaタnーdモaーllドP認W識M off in Master
かつ
and Slave
マスター/スレーブ全_↓てで
PWM OFF
↓
Cut FB output
FB出力ｶｯﾄ
スレ_Rー_eブ_cモ_oー_gnド_iﾞ認_ze識_{d slave mode}
かスレつ_{aーnブdのaPlWl MPがW全MてoOfFfFin Slave}
↓
↓
FB出力カッCトut FB output
Slave IC
SUMPWM
CS
FB
Figure 19.
Connecting plural BD9422EFVs makes it a Master/slave, a DCDC in Master construct a system to drive LED driver. Here,
explanation of Master/slave operation in connecting 2 ICs.
[MSDET] Convertor for recognizing Master/slave
Detect the voltage of CS terminal to judge master or slave of itself. The CS terminal of slave is OPEN when the
Master/slave mode is used. The CS terminal is high due to being supplied constant current from IC inside. The CS terminal
of Master is connected a resistance for DCDC switching current detection and swing 0V to 0.45V on operating. Convertor
can detect the differences of the voltage, which is a Master/slave recognizing signal.
[SUMPWMDET] Converter for all PWM signal detection
SUMPWM terminal is connected a switch that is ON when the PWM signal is high and a pull down resistance 100kΩ.
SUMPWM terminal becomes high more than one PWM signals are high.
When the SUMPWM terminal is connected between master and slave, it can judge if more than one signals of the entire
PWM signal in master/slave becomes high.
The operation of error amplifier part is decided by the signal of MSDET and SUMPWM
1.Error amplifier output part Diode/non diode
If the IC recognizes slave mode, the diode is connected to error amplifier output and cut the supply of sink side of error
amplifier.
2.Error amplifier output part Pull up resistance/ non pull up resistance
If the IC recognizes master mode and the PWM of slave become ON more than one, the pull up resistance is connected.
3. Error amplifier output FB output cut
In master recognizing, if all the PWM signals are OFF error amplifier output is cut.
In slave recognizing, if all the PWM signals of slave side are OFF error amplifier output is cut.
These are collected, the table below.
Use for Master/Slave mode
Master
Master
Slave
Error Amplifier output
source sink pull up
PWM ON PWM ON
○
○
-
PWM ON PWM OFF
○
○
-
PWM OFF PWM ON
○
○
○
PWM OFF PWM OFF
-
-
-
Slave
Error Amplifier output
source sink pull up
-
○
-
-
-
-
-
○
-
-
-
-
Use for Master only
Master
PWM ON
PWM OFF
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TSZ22111・15・001
Master
Error Amplifier output
source sink pull up
○
○
-
-
-
-
15/25
TSZ02201-0F1F0C100210-1-2
31.May.2013 Rev.003