ROHM BD9207FPS Technical data

LED Driver series for lighting

Step-down type with 1.5A output

BD9207FPS

No.09093EAT01

●Description BD9207FPS is a LED driver with built-in step-down switching regulator and incorporates the bui lt-in switching MOS EFT of Pch. Feedback voltage is as low as 0.2V and can suppress the loss on the sense resistance of LED. It is operated by PWM method with an oscillating frequency of 900 KHz and can use smaller coil than a switching regulator of low-frequency operation.

●Features

1) Maximum switching current of 1.5A

2) Built-in Pch switching MOS FET for high efficiency

3) Low loss because feedback voltage is as low as 0.2V

4) High oscillating frequency of 900KHz (Fixed)

5) Built-in soft start function

6) Built-in overcurrent protection circuit (OCP)

7) Built-in thermal shutdown circuit (TSD)

8) ON/OFF of output is possible by STBY terminal.

9) Compact surface-mount TO252S-5 package

●Applications ・For use in the light sources of PPC ・Printer etc. and the LCD backlights of LED lighting apparatus & monitor ・Note PC etc.

●Absolute maximum ratings（Ta=25℃）

Parameter Symbol Supply voltage（VCC-GND） Vcc 36 V STBY-GND Voltage V OUT-GND Voltage V INV-GND Voltage V Maximum switching output current. Iout 1.5(*1) A Allowable loss Pd 800(*2) mW Operating temperature range Topr -20 ~ +85 ℃ Storage temperature range Tstg -55 ~ +150 ℃

(*1)Regardless of the listed rating, do not exceeded Pd, ASO or Tjmax=150℃. (*2) Without heat sink, reducing by the 16 mW every 1℃ rise in temperature. (above 25℃)

36 V

STBY

36 V

OUT

5 V

INV

Rating Unit

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BD9207FPS

●Operating range (Ta=-40～+85℃)

Parameter Symbol

Supply voltage VCC 8.0 - 35.0 V Output voltage Vo 2.5 -

●Electrical characteristics（Unless otherwise specified, Ta=25℃,VCC=24V,STBY=3V） Parameter Symbol

Output MOS ON resistance Ron - 1.0 1.5 Ω Oscillating frequency fosc 810 900 990 kHz Overcurrent detection current Iocp 1.6 - - A

INV terminal threshold voltage

INV terminal bypass current IINV - 1 2 μA STBY terminal control

voltage STBY terminal inflow current Istby 5 15 30 μA

Circuit current Icc - 5 12 mA Standby current Ist - 0 5 μA

Soft start time Tss - - 10 ms

Without radiation-proof design.

ON VSTBYON 2.0 - 36 V OFF VSTBYOFF -0.3 - 0.3 V

Min. Typ. Max.

VINV 0.194 0.200 0.206 V

Limit

0.8×

(VCC-Io×Ron)

Limit

Min. Typ. Max.

Unit Conditions

V

Technical Note

Unit Conditions

VINV=0.2V

STBY=3V

STBY＝0V

STBY＝0→3V

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BD9207FPS

●Block diagram

VCC

1

VREF

PWM COMP

DRIVER

STBY

5

OSC

STBY

TSD

CTL LOGIC

OUT

2

OCP

Error AMP

INV

4

SS

FIN

GND

●Outline drawing of package ●Explanation of terminal

Pin No. Pin Name Function

1 VCC

2 OUT

3※

OUT

FIN GND Ground terminal

4 INV

5 STBY

※Used normally in open-circuit condition

TO252S-5（Unit：mm）

Technical Note

Supply voltage terminal

Drain terminal of built-in PMOS FET

Output voltage feedback terminal

ON/OFF control terminal

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BD9207FPS

●Functional explanation of block

・ VREF

The constant voltage to be temperature-compensated is created from the voltage inputted from VCC terminal.

・ OSC

Triangular wave with an oscillating frequency of 900 KHz is created, as an input of PWM comparator, by built-in resistor and capacitor.

・ Error AMP

It detects, at INC terminal, the voltage of sense resistance terminal created by LEC current, and compares it to the reference voltage, and amplifies and outputs the differential voltage. (The reference voltage is 0.2V±3%)

・ PWM COMP

PWM COMP converts the output voltage of error amplifier into the pu lse-width modulation waveform and outputs it to DRIVER.

・ DRIVER

Push-pull FET driver takes in the PWM waveform and directly drives the Pch MOS FET that is built-in in the IC.

・ STBY

The ON/OFF control of output is performed by STBY terminal. The output becomes ON if STBY voltage is High level.

・ Thermal shutdown circuit (TSD)

TSD circuit protects the IC from runaway thermal operation or heat damage. TSD circuit detects the temperature of chip, and the circuit becomes off if the temperature reaches 175℃. For TSD detection and release, the hysteresis of 15℃ is set, so the malfunction caused by temperature variation is prevented.

・ Over Current Protection（OCP）

Out is turned off if the voltage difference between VCC – OUT, caused by the current flowing in the Pch MOS EFT built-in in OCP circuit, is detected and reaches the reference value of OCP. The OCP is not of latch type but of self-return type.

・ Soft start circuit (SS)

Soft start time is set by the built-in capacitor connected to SS circuit. The capacitor is charged when STBY terminal becomes High level and the IC is started. The soft start time is set at 4ms or so.

Technical Note

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