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PDF BD93942F Data sheet ( Hoja de datos )
| Número de pieza | BD93942F | |
| Descripción | White LED Driver | |
| Fabricantes | ROHM Semiconductor | |
| Logotipo |  |
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Datasheet
LED Drivers for LCD Backlights
White LED Driver for large LCD
Panels (DCDC Converter type)
BD93942F
General Description
BD93942F is a high efficiency driver for white LEDs and
designed for large LCDs. These ICs are built-in a boost
DCDC converters that employ an array of LEDs as the
light source. BD93942F have some protect function
against fault conditions, such as the over-voltage
protection (OVP), the over current limit protection of
DCDC (OCP), the short circuit protection (SCP), the
open detection of LED string. Therefore BD93942F are
available for the fail-safe design over a wide range
output voltage.
Key Specification
Operating power supply voltage range: 9.0V to 35.0V
LED minimum current
30mA
LED maximum current:
150mA
Oscillator frequency:
150kHz (RT=100kΩ)
Operating Current:
3.7mA (Typ.)
Operating temperature range:
-40°C to +85°C
Features
4ch LED constant current driver and DC/DC converter
Maximum LED Current: 150mA
LED Feedback Voltage: 0.45V (@ILED=150mA)
so lower heat. Adjustable Feed Back Voltage
by following LED Current setting.
2% LED current accuracy (ADIM=2.5V,
when each LED is set to 100mA)
Analog current (Linear) dimming at ADIM pin
LED pin rating 60V
Individual detection and individual LED OFF for both
open and short circuits
Built-in ISET pin short-circuit protection circuit
FET’s Gate (N pin) is driven by 5.8V swing
Built-in Vout discharge circuit for shutdown
Built-in Vout overvoltage protection (OVP) /
reduced voltage protection (SCP) circuit
SOP16 package
Applications
TV, Computer Display, Notebook, LCD Backlighting
Package
SOP16
W(Typ.) x D(Typ.) x H(Max.)
10.00mm x 6.20mm x 1.71mm
Typical Application Circuit
Figure 1. SOP16
VIN
VIN
Inductor
Diode
CIN
FET
PGND
AGND
COUT
REG58
CREG
RN2
RCS DN RN1
ROVP1
ROVP2
RRT
COVP
RFB CFB1
ADIM
RISET
REG58
N
GND
CS
RT
OVP
SSFB
ISET
ADIM
STB
VCC
LED4
LED3
LED2
LED1
PWM
ON/ OFF
RVCC
CVCC
CLED4
CLED3
CLED2
CLED1
PWM
Figure 2. Typical Application Circuit
○Product structure：Silicon monolithic integrated circuit
.www.rohm.com
© 2015 ROHM Co., Ltd. All rights reserved.
TSZ22111・14・001
○This product has not designed protection against radioactive rays
1/26
TSZ02201-0F5F0C100050-1-2
12.Aug.2015 Rev.002
1 page  
BD93942F
Pin Descriptions (SOP16)
Pin No
Pin Name
1 REG58
2 CS
3N
4 GND
5 OVP
6 STB
7 LED1
8 LED2
9 LED3
10 LED4
11 PWM
12 ISET
13 SSFB
14 RT
15 ADIM
16 VCC
In/Out
Out
In
Out
-
In
In
Out
Out
Out
Out
In
Out
In/Out
Out
In
In
Function
Power supply for N pin
DC/DC output current detection and OCP detection pin
DC/DC switching output pin
Ground pin
Overvoltage protection detection pin
Enable pin
Output pin 1 for LED
Output pin 2 for LED
Output pin 3 for LED
Output pin 4 for LED
External PWM light modulation signal input pin for LED1-4
LED current setting resistor connection pin
Soft start setting, Loop compensation setting pin
DC/DC drive frequency setting resistor connection pin.
Analog dimming DC voltage input pin
Power supply pin
Datasheet
Rating [V]
-0.3 to 7
-0.3 to 7
-0.3 to 7
-
-0.3 to 36
-0.3 to 36
-0.3 to 60
-0.3 to 60
-0.3 to 60
-0.3 to 60
-0.3 to 36
-0.3 to 7
-0.3 to 7
-0.3 to 7
-0.3 to 36
-0.3 to 36
www.rohm.com
© 2015 ROHM Co., Ltd. All rights reserved.
TSZ22111・15・001
5/26
TSZ02201-0F5F0C100050-1-2
12.Aug.2015 Rev.002
5 Page 
BD93942F
Startup operation and soft start (SSFB) capacitance setting
The following section describes the sequence for the startup of this IC.
①
STB
OSC
SSFB
Soft-Start(ISS=10uA)
IFB(Sink, Source)=±100uA)
5V
Q D PWM
COMP
OSC
DRIVER
Datasheet
VOUT
N
CS
PWM
N
VOUT
ILED
LED_OK
②
③
④
⑤
⑥
Figure 11. Startup waveform
SSFB
RSSFB
CSSFB
LED_OK
VLED
LED_DRIVER
LED
PWM
Figure 12. Circuit behavior at startup
Description of startup sequence
(1) Set the STB and PWM pin to “ON”.
(2) Set all systems to “ON”, SSFB charge will be initiated.
(3) Since the SSFB pin reach the lower limit of the internal sawtooth wave of the IC, the DC/DC converter operates to
start VOUT voltage rising.
(4) The Vout voltage continues rising to reach a voltage at which LED current starts flowing.
(5) When the LED current reaches the set amount of current, the startup operation is completed.
(6) After that, conduct normal operation following the feedback operation sequence with the LED pins.
If the SSFB pin sink/source current is ±100uA, the LED protection function will be activated.
SSFB capacitance setting procedure
As aforementioned, this IC stops DC/DC converter when the PWM pin is set to Low level and conducts step-up operation
only in the section in which the PWM pin is maintained at High level. Consequently, setting the PWM duty cycle to the
minimum will extend the startup time. The startup time also varies with application settings of output capacitance, LED
current, output voltage, and others.
Startup time at minimum duty cycle can be approximated according to the following method:
Make maeasurement of VOUT startup time with a 100% duty cycle, first. Take this value as “Trise100”.
The startup time “Trise_min” for the relevant application with the minimum duty cycle is given by the following equation.
Trise_ min
Trise_100[Sec]
Min_ Duty[ratio]
[Sec]
However, since this calculation method is just for approximation, use it only as a guide.
Assuming that the SSFB pin voltage is VSSFB, the time is given by the following equation:
TSSFB
CSSFB[F ] VSSFB[V
10[A]
]
[Sec]
As a result, it is recommended to make SSFB capacitance setting so that “TSSFB” will be greater than “Trise_min”
www.rohm.com
© 2015 ROHM Co., Ltd. All rights reserved.
TSZ22111・15・001
11/26
TSZ02201-0F5F0C100050-1-2
12.Aug.2015 Rev.002
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet BD93942F.PDF ] | |
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