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PDF BD9489F Data sheet ( Hoja de datos )
| Número de pieza | BD9489F | |
| Descripción | White LED Driver | |
| Fabricantes | ROHM Semiconductor | |
| Logotipo |  |
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Datasheet
LED Drivers for LCD Backlights
1ch Boost up type
White LED Driver for large LCD
BD9489F
1.1 General Description
BD9489F is a high efficiency driver for white LEDs and is
designed for large LCDs. BD9489F has a boost DCDC
converter that employs an array of LEDs as the light
source.
BD9489F has some protect functions against fault
conditions, such as over-voltage protection (OVP), over
current limit protection of DCDC (OCP), LED OCP
protection, and Over boost protection (FBMAX).
Therefore it is available for the fail-safe design over a
wide range output voltage.
Key Specifications
Operating power supply voltage range: 9.0V to 35.0V
Oscillator frequency of DCDC: 150kHz (RT=100kΩ)
Operating Current:
2.6mA(Typ.)
Operating temperature range:
-40°C to +85°C
1.2 Package(s)
SOP16
W(Typ) x D(Typ) x H(Max)
10.00mm x 6.20mm x 1.71mm
Pin pitch 1.27mm
Features
DCDC converter with current mode
As PWM=L, the retaining function of Vout, FB voltage
VOUT discharge function at shutdown
LED protection circuit (Over boost protection, LED
OCP protection)
Over-voltage protection (OVP) for the output voltage
Vout
Adjustable soft start
Adjustable oscillation frequency of DCDC
Wide range of analog dimming 0.2V to 3.0V
UVLO detection for the input voltage of the power
stage
Applications
TV, Computer Display, LCD Backlighting
Figure 1. SOP16
1.3 Typical Application Circuit(s)
VCC
VIN
Vout
VCC
REG58
STB
RT
SS
CP
PWM
ADIM
UVLO OVP
GATE
CS
DIMOUT
ISENSE
FB
GND
Rs
Figure 2. Typical Application Circuit
○Product structure：Silicon monolithic integrated circuit
.www.rohm.com
© 2013 ROHM Co., Ltd. All rights reserved.
TSZ22111・14・001
○This product has not designed protection against radioactive rays
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TSZ02201-0F1F0C100250-1-2
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1 page  
BD9489F
2.1 Pin Function
No.
Pin
Name
1 VCC
2 STB
3 OVP
4 UVLO
5 SS
6 PWM
7 CP
8 ADIM
9 RT
10 FB
11 ISENSE
12 GND
13 DIMOUT
14 GATE
15 CS
16 REG58
IN/OUT
In
In
In
In
Out
In
Out
In
Out
Out
In
-
Out
Out
In
Out
Function
Power supply pin
IC ON/OFF pin
Over voltage protection detection pin
Under voltage lock out detection pin
Slow start setting pin
External PWM dimming signal input pin
Charge timer for abnormal state
ADIM signal input pin
DC/DC switching frequency setting pin
Error amplifier output pin
LED current detection input pin
-
Dimming signal output for NMOS
DC/DC switching output pin
DC/DC output current detect pin,
OCP input pin
5.8V output voltage pin and shutdown
timer pin
Rating [V]
-0.3 to 36
-0.3 to 20
-0.3 to 20
-0.3 to 20
-0.3 to 7
-0.3 to 20
-0.3 to 7
-0.3 to 20
-0.3 to 7
-0.3 to 7
-0.3 to 7
-0.3 to 7
-0.3 to 7
-0.3 to 7
-0.3 to 7
Datasheet
www.rohm.com
© 2013 ROHM Co., Ltd. All rights reserved.
TSZ22111・15・001
5/36
TSZ02201-0F1F0C100250-1-2
29.Oct 2014 Rev.002
5 Page 
BD9489F
Datasheet
○Pin 13: DIMOUT
This is the output pin for external dimming NMOS. The table below shows the rough output
logic of each operation state, and the output H level is REG58. Please refer to “3.5 Timing
Chart” for detailed explanations, because DIMOUT logic has an exceptional behavior.
Please insert the resistor RDIM between the dimming MOS gate to improve the over shoot
of LED current, as PWM turns from low to high.
Status
Normal
Abnormal
DIMOUT output
Same logic to PWM
GND Level
Figure 15. DIMOUT terminal circuit
○Pin 14: GATE
example
This is the output terminal for driving the gate of the boost MOSFET. The high level
is REG58. Frequency can be set by the resistor connected to RT. Refer to <RT> pin description for the frequency setting.
When PWM=L, IC holds the OVP voltage at the edge of PWM=H to L, and operates to hold the adjacent voltage. Please
refer to section “3.5 Timing Chart”.
When PWM=L, IC outputs the necessary boost pulse to startup or to keep the output voltage. Please refer to section “2.8
The Retaining Function of The Output Voltage”.
As the retaining of the output voltage is enable, the GATE pulse is not output at the boundary of PWM logic such as High
to Low, or as Low to High.
Figure16. The GATE waveform as PWM dimming
As the retaining of the output voltage is disable, the GATE pulse is synchronized with the timing of PWM=L -> H
○Pin 15: CS
The CS pin has two functions.
1. DC / DC current mode Feedback terminal
The inductor current is converted to the CS pin voltage by the sense resistor RCS.
This voltage compared to the voltage set by error amplifier controls the output
pulse.
2. Inductor current limit (OCP) terminal
The CS terminal also has an over current protection (OCP). If the voltage is more
than 0.4V(typ.), the switching operation will be stopped compulsorily. And the
next boost pulse will be restarted to normal frequency.
In addition, the CS voltage is more than 1.0V(typ.) during four GATE clocks, IC
will be latch off. As above OCP operation, if the current continues to flow
nevertheless GATE=L because of the destruction of the boost MOS, IC will stops
the operation completely.
Both of the above functions are enabled after 300ns (typ) when GATE pin
asserts high, because the Leading Edge Blanking function (LEB) is included Figure 17. CS terminal circuit example
into this IC to prevent the effect of noise.
Please refer to section “3.3.1 OCP Setting / Calculation Method for the Current Rating of DCDC Parts”, for detailed
explanation.
If the capacitance Cs in the right figure is increased to a micro order, please be careful that the limited value of NMOS
drain current Id is more than the simple calculation. Because the current Id flows not only through Rcs but also through
Cs, as the CS pin voltage moves according to Id.
○Pin 16: REG58
This is the 5.8V(typ.) output pin. Available current is 15mA (min).
And this terminal is also used as timer for discharging DCDC output capacitor.
Please refer to section“3.2.2 Shutdown Method and REG58 Capacitance Setting”, for detailed explanation.
www.rohm.com
© 2013 ROHM Co., Ltd. All rights reserved.
TSZ22111・15・001
11/36
TSZ02201-0F1F0C100250-1-2
29.Oct 2014 Rev.002
11 Page | ||
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| PDF Descargar | [ Datasheet BD9489F.PDF ] | |
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