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BD9E151NUX

TSZ02210-0Q3Q0AZ00160-1-2

© 2013 ROHM Co., Ltd. All rights reserved

2013.07.17 Rev.001

Datasheet

Datasheet

www.rohm.com

TSZ22111・15・001

Description of Blocks

1. Reference

This block generates reference voltage and current. It start operation by applying EN=H.

It provides reference voltage and current to error amplifier, oscillator, and etc.

2. REG

This is a gate drive voltage generator and 5.5V regulator for internal circuit power supply.

3. OSC

This is a precise wave oscillation circuit with operation frequency fixed to 600 kHz

4. Soft Start

This block does Soft Start to the output voltage of DC/DC converter, and prevents in-rush current during Start-up.

Soft Start Time set by the capacitor connected to SS pin and SS charge current is the time from EN Pin start-up

to reaching to 1.0V.

5. ERROR AMP

This is an error amplifier that detects output signal, and outputs PWM control signal. Internal reference voltage is set

to 1.0V. Connect phase compensation components between this pin and ground (ref. p.11).

6. OVP

The OVP circuit includes an overvoltage comparator to compare the FB pin voltage and internal thresholds. When the

FB pin voltage goes above 110%×FB, the high-side MOSFET will be forced off. When the FB pin voltage falls

below 105%, the high-side MOSFET will be enabled again.

7. ICOMP

The BD9E151NUX implements current mode control that uses the VC pin voltage to turn off the high-side MOSFET on a

cycle by cycle basis. Every cycle the switch current and the COMP pin voltage are compared; when the peak inductor

current intersects the VC pin voltage, the high-side switch is turned off. During overcurrent conditions that pull the output

voltage low, the error amplifier responds by driving the COMP pin high, causing the switch current to increase.

8. OCP

This is a circuit to protect the high-side FET from overcurrent. Every cycle the switch current and the reference voltage

of overcurrent protection are compared; when the peak inductor current intersects the reference voltage, the high-side

switch is turned off. Once overcurrent is detected, the device will stop and VC pin voltage will be reset and SS pin

voltage will be discharged by 2uA (hiccup operation). Then SS pin voltage reaches to less than 0.1V, IC will restart.

9. High-side MOSFET

This is a 30V/80mΩ high-side MOSFET that converts inductor current of DC/DC converter.

Because the current limiting of this FET is 1.6A included ripple current, please use at within1.6A.

10. UVLO

This is a low voltage error prevention circuit.

This prevents internal circuit error during increase of power supply voltage and during decline of power supply voltage.

It monitors VIN pin voltage and internal REG voltage, and when VIN voltage becomes 5.2V and below, it turns OFF all

output FET and turns OFF DC/DC comparator output and Soft Start circuit resets.

Now this Threshold has hysteresis of 200mV.

11. TSD

This is a heat protect circuit.

When it detects an abnormal temperature exceeding maximum junction temperature (Tj=150℃), it turns OFF all Output

FET, and turns OFF DC/DC converter output. When temperature falls, it automatically returns.

12. EN

When a Voltage of 2.4V or more is applied, it turns ON, at Open or 0V application, it turns OFF.

About 700kΩ Pull-down Resistance is contained within the Pin.