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BD1754HFN-TR

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P19
10/16
BD1754HFN
Datasheet
TSZ02201-0G3G0C200060-1-2
9.NOV.2012 Rev.001
www.rohm.com
© 2012 ROHM Co., Ltd. All rights reserved.
TSZ22111･15･001
(3) Circuit example when the EN pin is powered on at all times
Rs
VIN
ISET
GND
Current
DAC
UPIC
6
EN
L2L1
0.1µ
Cs
L
4L3
(When ILED-max =32mA)
120kΩ
Cin
R
ISE
T
Figure 18. Circuit example when the EN pin is powered on at all times
This figure shows a circuit example when the EN pin is powered on at all times. To prevent a rush current from
occurring in the driver, it is necessary to apply voltages to the VIN pin and the LEDs prior to powering the current driver
ON. Mount an RC filter between the VIN and the EN pins to delay the EN pin rising against the power-supply voltage
rising. Determine the resistance value with which the LED current value is maximized and then connect such resistor
between the ISET and the GND pins.
(4) Circuit example when performing a PWM brightness control
VIN
ISET
GND
Current
DAC
UPIC
6
EN
L2L1
0.1µF
PWM
1MΩ
120kΩ
L4L3
Cin
R
ISET
Figure 19. Circuit example when performing a PWM brightness control
This figure shows a circuit example when performing a PWM brightness control. Through switching the ISET resistance
value by the PWM input signal, the LED current is outputted under a PWM mode. The EN signal is controlled by an
applied voltage level. In the circuit example shown above, the LED current value is changed to 3.43 mA in 0 % of the
PWM duty cycle, 17.72 mA in 50 % of that and 32 mA in 100 % of that.
11/16
BD1754HFN
Datasheet
TSZ02201-0G3G0C200060-1-2
9.NOV.2012 Rev.001
www.rohm.com
© 2012 ROHM Co., Ltd. All rights reserved.
TSZ22111･15･001
(5) Circuit example when driving a large current with only one LED powered on.
VIN
ISET
GND
Current
DAC
UPIC
6
EN
L2L1
0.1µF
L4L3
(When ILED-max =32mA)
120kΩ
ILED=128mA
Cin
R
ISE
T
Figure 20. Circuit example when driving a large current with only one LED powered on.
This figure shows a circuit example when driving a large current through all of four channels with only one LED
powered on. By shorting out all the LED driver pins, in the example of using 120 kΩ R
ISET
, a current up to 128 mA (32
mA x 4) can be driven. In this example, the brightness can be adjusted in 64 gradations with 2 mA step (0.5 mA
step/channel x 4 channels). For higher current values, using 60 kΩ R
ISET
allows a current up to 256 mA to be driven
into one of the LEDs. The power ON/OFF and the brightness of the LEDs are controlled through the EN pin in
accordance with the UPIC format.
(6) Circuit example when making the eight LEDs available by connecting the two BD1754HFN drivers
VIN
ISET
GND
Current
DAC
UPIC
6
EN
L2 L1
0.1µF
L4 L3
(When ILED-max =32mA)
120kΩ
ILED=32mA
VIN
ISET
GND
Current
DAC
UPIC
6
EN
L2L1
L4 L3
(When ILED-max =32mA)
120kΩ
ILED=32mA
0.1µF
Cin
R
ISE
T
Cin
R
ISE
T
Figure 21. Circuit example when making the eight LEDs available by connecting the two BD1754HFN drivers
This figure shows a circuit example when making eight LEDs available by connecting two BD1754HFN drivers.
By connecting the control signals to the EN pins in parallel, the eight LED channels can be controlled concurrently.
This parallel connection scheme can increase the number of the LED channels further as necessary (such as twelve,
sixteen, or more). Determine the resistance value with which the LED current value is maximized and then connect
such resistor between the ISET and the GND pins. The power ON/OFF and the brightness of the LEDs are controlled
through the EN pin in accordance with the UPIC format.
12/16
BD1754HFN
Datasheet
TSZ02201-0G3G0C200060-1-2
9.NOV.2012 Rev.001
www.rohm.com
© 2012 ROHM Co., Ltd. All rights reserved.
TSZ22111･15･001
(7) Circuit example when connecting the two LEDs to each of the channels in series
VIN
ISET
GND
Current
DAC
UPIC
6
EN
L4L3L2L1
Power Supply2=6.2~7V
0.1µF
120kΩ
The voltage value of L* pin must
be VIN-1.4 V at the maximum
when the LED is powered ON.
Power Supply1
(When ILED-max =32mA)
(Maximum rating = 7.0 V)
On the assumption that Vf is 3 V
(Ex.)
Figure 22. Circuit example when connecting the two LEDs to each of the channels in series
This figure shows a circuit example when making 8 (2 x 4) LEDs available by connecting two LEDs to each of the
channels in series. In this example, when Vf is set to approx. 3 V in order to ensure the voltage to L1 through L4 pins, it
is necessary to apply a voltage of 6.2 V (3 V x 2 LED’s in series + 0.2 V of the minimum voltage value of the driver pin)
or higher to the LED anode pin as its power supply voltage. Pay attention that the voltage should not exceed the 7.0-V
maximum rating of the L1 through L4 pins. Determine the resistance value with which the LED current value is
maximized and then connect such resistor between the ISET and the GND pins. The power ON/OFF and the
brightness of the LEDs are controlled through the EN pin in accordance with the UPIC format.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P19

BD1754HFN-TR

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Description:
LED Lighting Drivers 4 LEDs 2.7-5.5V 32mA Max Curr
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