Technical Note
6/10
www.rohm.com
2011.06 - Rev.B
© 2011 ROHM Co., Ltd. All rights reserved.
BD1604MUV, BD1604MVV
●Description of Block Operations
1) LED light control and current control
When LED lights are controlled, H- or L-level voltage is applied to respective control pins.
Current control in the BD1604MUV/MVV can take place via a resistance connected to the ISET pin.
ON/OFF control
SEL2 SEL1 SEL0 LED1 LED2 LED3 LED4
0 0 0 OFF OFF OFF ON
0 0 1 OFF OFF ON OFF
0 1 0 OFF ON OFF OFF
0 1 1 ON OFF OFF OFF
1 0 0 OFF OFF ON ON
1 0 1 OFF ON ON ON
1 1 0 ON ON ON ON
1 1 1 OFF OFF OFF OFF
Rset: See the following table. 0: 0V, 1: VBAT
When handling pins, the LED pins must be connected to VBAT so long as LED is always OFF.
Current control
Rset 165kΩ 97.6kΩ 48.7kΩ 32.4kΩ 24.3kΩ 16.2kΩ
ILED 3mA 5mA 10mA 15mA 20mA 30mA
The LED current can be changed by the Rset value.
ILED=480/Rset
The above expression can be used for approximation.
2) Low supply voltage detection circuit (UVLO)
When the IC-applied supply voltage drops, all the circuits including the DC/DC converter are stopped. When supply voltage
drops to a detecting voltage, UVLO is activated. When it rises, UVLO is automatically released.
3) Soft start by DC/DC converter startup
When a DC/DC converter is started, soft start is enabled so that output voltage can be increased gradually to prevent output
voltage overshooting.
●Application Parts Selection Method
Capacitor (Use the ceramics parts with good frequency and temperature characteristics.)
Symbol Recommended value Recommended part Type
Cout,Cin,C1,C2 1μF GRM188B11A105KA61B(MURATA) Ceramics capacitor
Resistance
Symbol Recommended value Recommended part Set Current Value
Rset
16kΩ
MCR006YZPF Series (ROHM)
30mA
~
~
240kΩ 2mA
Connect an input bypass capacitor (CIN) between VBAT and GND pin in proximity. In addition, connect an output capacitor
between VOUT and GND pins in proximity. Connect a capacitor between C1P and C1N and also a capacitor between C2P
and C2N in proximity to the chips. Connect a resistance in proximity to the ISET pin.
When other than these parts are used, the equivalent parts must be used.
