Datasheet

Datasheet

4/36

BD81A24MUV-M/EFV-M

TSZ02201-0T3T0C600070-1-2

© 2016 ROHM Co., Ltd. All rights reserved.

2016.10.19 Rev.003

www.rohm.com

TSZ22111・15・001

80

90

100

110

120

-40

-25

-10

5

20

35

50

65

80

95

110

125

Ta [℃]

Ta vs ILED

⊿VOUT=50mV

⊿VOUT=100mV

⊿VOUT=200mV

<Caution of LED current setting>

decrease. LED current supply value will depends on the amount of ripple in output voltage (VOUT). The figure below shows

the temperature and the possible LED current maximum value settings, please adjust the ripple voltage in such a way that

the LED current value setting will fall within the range as shown on the graph below. (∆VOUT: Output Ripple Voltage) Please

refer P22, there is the detail information of VOUT ripple voltage.

Figure 5. Temperature (Ta) vs Output LED Current (ILED)

(2) PWM Intensity Control

use PWM dimming, please set the PWM terminal to HIGH. Output light intensity is greatest at 100% input

3. Buck-Boost DC/DC Controller

(1) Number of LED in Series Connection

In this IC, the output voltage of the DC/DC converter (VOUT) is controlled by LED cathode voltage (LED1–4 terminal

voltage) becomes 1.0V (Typ). When two or more LED are operating at the same time, the LED terminal voltage that

connects the highest LED Vf row is held at 1.0V (Typ). Then the voltages of other LED terminal will increased only LED VF

tolerance. Please decide LED VF tolerance by using the description as shown below:

LED series number x LED VF tolerance voltage < Short Detection Voltage 4.2V (Min) － LED Control Voltage 1.1V (Max)

(2) Over Voltage Protection (OVP)

The output of the DC/DC converter (VOUT) should be connected to the OVP pin via voltage divider. If OVP terminal voltage

is over 2.0V (Typ), Over Voltage Protection (OVP) is active and stop the DCDC switching. In determining an appropriate

trigger voltage for OVP function, consider the total number of LEDs in series and the Maximum variation in VF. When OVP

terminal voltage drops to 1.94V (Typ) after OVP operation, the OVP will be released. If ROVP1 is GND side resistance,

ROVP2 is output voltage side resistance and output voltage is VOUT, OVP will occur at below equation.

[ ]

{(

1[

] +

2[

])/1[

]} × 2.0[ ]

PWM

(2V/div)

ILED

(50mA/div)

PWM

(2V/div)

ILED

(50mA/div)

500ns/div

1ms/div