Technical Note

6/10

www.rohm.com

2011.06 - Rev.B

© 2011 ROHM Co., Ltd. All rights reserved.

BD1604MUV, BD1604MVV

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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.

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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.