BD9DA00MF datasheet(5/53 Pages) ROHM

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BD9DA00MF

Datasheet

TSZ02201-0J2J0AB01940-1-2

18.Mar.2025 Rev.001

www.rohm.com

TSZ22111 • 15 • 001

Description of Blocks

1. VREF

The VREF block generates the internal reference voltage.

2. REG

The REG block generates internal power supply. It outputs 3.0 V (Typ) and supplies to the control circuits and the Driver.

3. Soft Start

The Soft Start circuit slows down the rise of output voltage during startup, which prevents output voltage overshoot. The

soft start time can be set by connecting a capacitor to the SS/REF pin. For the setting method, refer to Selection of

Components Externally Connected 4. Soft Start Capacitor.

4. Error Amplifier

The Error Amplifier adjusts the Main Comparator input voltage to make the FB voltage equal to the internal reference

voltage.

5. Main Comparator

The Main Comparator compares the Error Amplifier output voltage and the voltage with Ramp superimposed on FB

voltage (VFB) . When VFB becomes lower than the Error Amplifier output voltage, the output turns high and reports to the

On-Time block that the output voltage has dropped below the control voltage.

6. On-Time

The On-Time block generates On Time. The designed On Time is generated after the Main Comparator output turns high.

The On Time is adjusted to control the frequency to be fixed even if input / output voltage is changed.

7. PGOOD

The PGOOD block is for power good function.

8. OVC

The OVC block is for output voltage clamp. When the FB pin voltage (VFB) becomes 104 % (Typ) or more of the FB

reference voltage VREF, the Low-Side FET turns on and suppresses the rise of the output voltage. When VFB becomes

103 % (Typ) or less of VREF, the device returns to normal operation.

9. OVP

The OVP block is for output over voltage protection. OVP function operates when the FB pin voltage VFB becomes 116 %

(Typ) or more of the FB reference voltage VREF, and it depends on the device operation mode. Refer to Function

Explanations 2. Protection (5) Over Voltage Protection (OVP).

10. UVLO

The UVLO block is for under voltage lockout protection. The device shuts down when input voltage VIN falls to 1.85 V

(Typ) or less, or VCC voltage VCC falls to 2.5 V (Typ) or less.

11. BSTDET

The BSTDET block detects the low voltage between the SW and BST (ΔVBST-SW). The Low-Side FET turns on and

charges a bootstrap capacitor when ΔVBST-SW is 2.1 V (Typ) or less.

12. TSD

The TSD block is for thermal protection. The device shuts down when the junction temperature Tj reaches to 175 °C

(Typ) or more. When Tj drops, the device restarts with a hysteresis of 25 °C (Typ).

13. HOCP

The HOCP block is for over current protection of the High-Side FET. When the current that flows through the High-Side

FET reaches the over current limit IHOCP = 17.5 A (Typ), the device turns off the High-Side FET and turns on the Low-

Side FET.

14. LOCP

The LOCP block is for over current protection of the Low-Side FET. While the current that flows through the Low-Side

FET over the value of over current limit, the device keep turning on the Low-Side FET.

15. SCP

The SCP block is for short circuit protection. After 3 ms (Typ) from the beginning of soft start, and after SS/REF voltage

(VSSREF) reaches 0.6 V (Typ), if VFB is 80 % (Typ) of FB reference voltage VREF or less, or over current protection is

detected for 31 consecutive cycles, the device shuts down for 117 ms (Typ). After 117 ms shutdown, the device restarts.

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