Datasheet

Datasheet

7/36

BD81A24MUV-M/EFV-M

TSZ02201-0T3T0C600070-1-2

© 2016 ROHM Co., Ltd. All rights reserved.

2016.10.19 Rev.003

www.rohm.com

TSZ22111・15・001

(1) Under-Voltage Lock Out (UVLO)

The UVLO shuts down all the circuits except VREG when VCC<3.5V (Typ) or VREG <2.0V (Typ). And UVLO is

released by Vcc>4.0V (Typ) and VREG>3.5V (Typ).

(2) Thermal Shut Down (TSD)

The TSD shuts down all the circuits except VREG when the Tj reaches 175°C (Typ), and releases when the Tj becomes

below 150°C (Typ).

(3) Over-Voltage Protection (OVP)

The output voltage of DC/DC is detected from the OVP terminal voltage, and the over-voltage protection will activate if

the OVP terminal voltage becomes greater than 2.0V (Typ). When OVP is activated, the switching operation of the

DC/DC turns off. And OVP terminal becomes less than 1.94V (Typ), OVP is released and the switching operation of the

DC/DC turns on.

(4) Over-Current Protection (OCP)

The OCP detects the coil current by monitoring the voltage of the high-side resistor, and activates when the CS voltage

When the OCP is activated, the switching operation of the DC/DC turns off. And CS voltage becomes over than

Vcc-0.2V (typ), OCP is released and the switching operation of the DC/DC turns on.

(5) Short Circuit Protection (SCP)

When the LED terminal voltage becomes less than 0.3V (Typ) or OVP terminal becomes less than 0.57V (typ), the

built-in counter operation will start and the latch will activate at oscillation frequency in 32770 count. In case of

fosc=300kHz, the count time is approximately 100ms. If the LED terminal voltage becomes over 0.3V or OVP terminal

becomes over 1.0V (typ) before 32770 count, the counter resets and SCP is not detected.

(6) LED Open Detection

When the LED terminal voltage is below 0.3V (Typ) and OVP terminal voltage more than 2.0V (Typ) simultaneously,

LED open is detected and latches off the open channel.

(7) LED Short Detection Circuit

If the LED terminal voltage becomes more than 4.5V (Typ), the built-in counter operation will start and the latch will

activate at oscillation frequency in 32770 count. In case of fosc=300kHz, the count time is approximately 100ms. During

PWM dimming, the LED Short Detect operation is carried out only when PWM=High. If the LED terminal voltage

becomes less than 4.5V (Typ) before 32770 count, the counter resets and LED Short is not detected.

When LED Short Detect function will not be used, SHDETEN terminal should be connected to VREG before starting.

When LED Short Detect function is used, the SHDETEN terminal should be connected to GND. In addition, it cannot

change SHDETEN voltage (High or Low) during normal operation.

(8) PWM Low Latch Off Circuit

After the EN is ON, the low interval of PWM input is counted by built-in counter. The clock frequency of counter is the

fosc Frequency, which is determined by RRT, and stops the operation of circuits except VREG at 32768 counts.

In case of fosc=300kHz, the count time is approximately 100ms.