BD9422EFV_15 Datasheet, PDF (9/30 Pages) Rohm – White LED Driver for large LCD panel

BD9422EFV
Datasheet
●3.1 Pin Configuration
1 pin. VCC
Power supply terminal of IC. The input range is 9 to 35V.
The operation starts over VCC＝7.5V(typ.) and the system stops under VCC=7.2V(typ.).
2 pin. FAIL
FAIL signal output terminal (NMOS open-drain). NMOS is OPEN at the normal operation so FAIL pin is Hi-Z. NMOS
becomes ON state (500 ohm typ.) at the abnormal detection. It is possible to select the FAIL type from latch type
(FAIL_MODE=L) or one shot pulse (FAIL_MODE=H).Please refer to the detail explanation＜38pin. FAIL_MODE terminal＞
3 pin. REG9V
REG9V is a 9 V output pin used delivering 20mA at
maximum for switching power supply of N terminal.
Use at a current higher than 20mA may affect the reference
voltage within IC, which may result in malfunction. It will also
cause heating of IC itself. Therefore it is recommended to set
the load as small as possible.
The characteristic of VCC line regulation at REG9V is shown
as figure. VCC must be used in more than 10.5V for stable
9V output.
Install an oscillation prevention ceramic capacitor (2.2 to 10μF)
nearest to VREG between VREG-AGND terminals.
REG9V ‐VCC (Line Regulation)
10
9
8
7
6
5
4
3
2
1
0
‐1 ⁰
5
10
15
20
25
30
35
VCC [V]
4 pin. N.C
Non connect pin. Please set it the open state or deal with connecting the GND.
Figure 12.
5 pin. N
Gate driving output pin of external NMOS of DC/DC converter with 0 to 9V (REG9V) swing. Output resistance of High side
is 2.5 ohm(typ.), Low side is 3.0 ohm(typ.) in ON state. The oscillation frequency is set by a resistance connected to RT pin.
For details, see the explanation of <34pin. RT terminal>.
6pin. PGND
Power GND terminal of output terminal, N driver:
7pin. CS
Inductor current detection resistor connecting terminal of DC/DC current mode: it transforms the current flowing through the
inductor into voltage by sense resistor R_CS connected to CS terminal, and this voltage is compared with that set in the error
amplifier by current detection comparator to control DC/DC output voltage. RCS also performs over current protection
(OCP) and stops switching action when the voltage of CS terminal is 0.45 V (typ.) or higher (Pulse by Pulse).
8 pin. OVP
OVP terminal is the detection terminal of overvoltage protection (OVP) and short circuit protection (SCP) for DC/DC output
voltage. Depending on the setting of the FAIL_MODE terminal, FAIL and CP terminal behave differently when an
abnormality is detected. For details, see the table for each protection operation is described in ●3.2 and ●3.3.
During the soft start (SS), there is a function which returns the OVP voltage to error amplifier to boost DC/DC output voltage
at all Low PWM (OVPFB function). After completion of SS, this function is disabled.
9 pin. M_DET
The Di OR output terminal of LED 1 to 6. The output is the voltage which is added a diode forward voltage(two diode stack)
to the lowest voltage among 6 LED terminals.
10pin. SUMPWM
This is a judging terminal if high signal is input to PWM terminal or not. Using in Master/slave mode, one SUMPWM
terminal is connected to another. And if any PWM signal becomes high between master and slave, the SUMPWM terminal
becomes high, too. For details, please refer to ●3.4 Connecting operation of Master/ slave.
11 to 16pin. LED1 to LED6
LED constant current driver output terminal. Setting of LED current value is adjustable by setting the VREF voltage and
connecting a resistor to S terminal. For details, see the explanation of <25 to 30pin. S1 to S6, 35pin. VREF >.
The PWM dimming frequency of LED current driver and upper/lower limit of the duty need to be set in a manner that
necessary linearity of PWM dimming characteristics can be secured referring to the following figures:
。
Start/Stop time of constant current driver (PWM pulse response)
Start-up time depends on the VREF value; the response becomes quick, so that voltage is high.
In the way of reference, the current response upon application of current rise rate and pulse PWM1us (current pulse) to
describe the dependence of VREF. It needs to be adequately verified with an actual device because the response rate may
vary with application conditions.
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TSZ02201-0F1F0C100210-1-2
1.Sep.2015 Rev.006