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Datasheet

Datasheet

BD81A34MUV-M BD81A34EFV-M

TSZ02201-0G3G0C600020-1-2

© 2014 ROHM Co., Ltd. All rights reserved.

16.Jan.2014 Rev.002

www.rohm.com

TSZ22111

・15・001

4. Self-Check Function

Table 2. Detection Condition of Each Protection Function and the Operation during Detection

Protection Function

Detection Condition

Operation During Detection

[Detection ]

[Release/ Cancellation]

UVLO

All Blocks Shuts down

(Except for VREG)

TSD

Tj>175°C

Tj<150°C

All Blocks Shuts down

(Except for VREG)

OVP

SS Pin Discharged

OCP

SS Pin Discharged

SCP

or

(100ms delay @300kHz)

EN or UVLO

Delay Counter starts and then

Latches Off all blocks

(Except for VREG)

LED Open Protection

EN or UVLO

Only the detected channel latches

OFF

LED Short Protection

(100ms delay @300kHz)

EN or UVLO

Only the detected channel latches

OFF (After the counter starts )

Note1. The FAIL1 and FAIL2 output is reset when EN=Low

⇒ High or UVLO Detection ⇒ Release/ Cancel

（EN＝Low or UVLO Detection are unfixed.）

Figure 17. Protection Flag Output Block Diagram

The operating status of the built-in protection circuitry is propagated to FAIL1 and FAIL2 terminals (open-drain outputs).

FAIL1 becomes low when TSD, OVP, OCP, or SCP protection is engaged, whereas FAIL2 becomes low when open or

short LED is detected. If the FAIL terminal will not be used as flag output, please make the FAIL terminal open or connect it

to GND. But if the FAIL terminal will be used as a flag output, it is recommended to pull-up the FAIL1, 2 terminals to VREG

terminal.

(1) Under-Voltage Lock Out (UVLO)

(2) Thermal Shut Down (TSD)

becomes below 150°C (Typ).

(3) Over-Current Protection (OCP)

The OCP detects the current through the power-FET by monitoring the voltage of the high-side resistor, and activates

When the OCP is activated, the external capacitor of the SS terminal becomes discharged and the switching operation

of the DC/DC turns off.

(4) 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 external capacitor of the SS

terminal becomes discharged and the switching operation of the DC/DC turns off.

EN=Low or UVLO

EN=Low or UVLO

FAIL1

FAIL2