XC9242 Series

2A Synchronous Step-Down DC/DC Converters

The XC9242 series is a group of synchronous-rectification step-down DC/DC converters with a built-in 0.11Ω(TYP.) P-ch MOS driver transistor and 0.12Ω(TYP.) N-ch MOS switching transistor, designed to allow the use of ceramic capacitors. The small on-resistances of these two internal driver transistors enable a high efficiency, stable power supply with an output current up to 2A. The XC9242 series has operating voltage range of 2.7V~6.0V and a 0.8V (±2.0%) reference voltage, and using externally connected resistors, the output voltage can be set freely from 0.9V.

With an internal switching frequency of 1.2MHz or 2.4MHz, small external components can be used.

The series have a high speed soft-start as fast as 1ms in typical for quick turn-on. It’s suitable for large-current application due to limit current is configured 4.0A in typical. During stand-by, all circuits are shutdown to reduce current consumption to as low as 1.0μA or less.

The integrated C_L discharge function which enables the electric charge at the output capacitor C_L to be discharged via the internal discharge switch located between the L_X and V_SS pins. Due to C_L discharge function, malfunction on L_X is prevented when Stand-by mode. With the built-in UVLO (Under Voltage Lock Out) function, the internal P-channel driver transistor is forced OFF when input voltage becomes 2.5V or lower. The series are available in USP-10B and SOP-8FD packages.

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Typical Application Circuit

Features

Packages

Package	SOP-8FD	Number of Pins	8
Pcs/Reel	1,000	Package Size(mm)	6.0 x 4.9 x 1.75
Package Dimensions [0.1MB] Taping Specifications [0.1MB] Package Power Dissipation [0.2MB] Perspective [0.1MB] Product Mass, MSL, Mounting Conditions [0.1MB] Control Plan [0.1MB]

Package	USP-10B	Number of Pins	10
Pcs/Reel	3,000	Package Size(mm)	2.6 x 2.9 x 0.6
Package Dimensions [0.1MB] Taping Specifications [0.1MB] Package Power Dissipation [0.1MB] Perspective [0.1MB] Product Mass, MSL, Mounting Conditions [0.1MB]

DATA SHEET

Technical Document

Quality Reports

FAQ

What is the soft-start function?

The function to soften the rise to prevent the inrush current.

How does the C_L discharge function work?

The function rapidly releases the charge remained in the C_L capacitor to make the V_OUT pin voltage zero. The V_OUT pin voltage does not reach zero immediately after being turned off by the CE function due to the charge remained in the connected C_L capacitor. While the charge in the C_L capacitor is gradually reaching zero, the LSI continues operating and does not work with the CE pin signal, which may cause a malfunction. This is why the discharge is required when turning off the CE pin. A larger capacitance of the capacitor needs longer time to be discharged.

What does C_L mean?

Load capacitor. Other companies often refer to it as C_OUT.

What is the standby current?

The current that flows through the IC in the standby mode. The standby mode means the state where the IC has been turned off by the CE function.

What does the FB product mean?

An IC for which any output voltage can be set by the reference voltage of the FB pins and the external dividing resistor. The output voltage is determined by the R_FB1 and R_FB2 values, using the following formula: V_OUT = Vref × (R_FB1 + R_FB2)/R_FB2

How does UVLO (under voltage lockout) work?

This circuit forcibly turns off the driver transistor when V_IN drops below the UVLO voltage. If the input voltage recovers to the value which is equal to the specified value or more, UVLO will be released to resume the switching operation. It is resumed by the soft-start function. The paused state by UVLO is not the shutdown. The pulse output is stopped, but the internal circuit is operating.