XC9236 Series

600mA Synchronous Step-Down DC/DC Converters

The XC9236 series is a group of synchronous-rectification type DC/DC converters with a built-in 0.42ΩP-ch MOS driver transistor and 0.52ΩN-ch MOS switching transistor, designed to allow the use of ceramic capacitors. Operating voltage range is from 2.0V to 6.0V (types A～C), 1.8V to 6.0V (types D～G). For the D/F types which have a reference voltage of 0.8V (±2.0%), the output voltage can be set from 0.9V by using two external resistors. The types A/B/C/E/G have a fixed output voltage from 0.8V to 4.0V in increments of 0.05V (±2.0%). The device provides a high efficiency, stable power supply with an output current of 600mA to be configured using only a coil and two capacitors connected externally. With the built-in oscillator, either 1.2MHz or 3MHz can be selected for suiting to your particular application.

The soft start and current control functions are internally optimized. During stand-by, all circuits are shutdown to reduce current consumption to as low as 1.0μA or less. The types B/F/G have a high speed soft-start as fast as 0.25ms in typical for quick turn-on. With the built-in UVLO (Under Voltage Lock Out) function, the internal P-channel MOS driver transistor is forced OFF when input voltage becomes 1.4V or lower.

The types B to G integrate 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. When the devices enter stand-by mode, output voltage quickly returns to the V_SS level as a result of this function.

Three types of package SOT-25, USP-6C, and USP-6EL and WLP-5-03 are available.

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Typical Application Circuit

Features

Packages

Package	SOT-25	Number of Pins	5
Pcs/Reel	3,000	Package Size(mm)	2.8 x 2.9 x 1.3
Package Dimensions [0.1MB] Taping Specifications [0.2MB] Package Power Dissipation [0.2MB] Perspective [0.1MB] Control Plan [0.1MB]

Package	USP-6C	Number of Pins	6
Pcs/Reel	3,000	Package Size(mm)	1.8 x 2.0 x 0.6
Package Dimensions [0.1MB] Taping Specifications [0.1MB] Package Power Dissipation [0.2MB] Perspective [0.1MB] Control Plan [0.1MB]

Package	USP-6EL	Number of Pins	6
Pcs/Reel	3,000	Package Size(mm)	1.8 x 2.0 x 0.4
Package Dimensions [0.1MB] Taping Specifications [0.1MB] Package Power Dissipation [0.1MB] Perspective [0.1MB] Control Plan [0.1MB]

Package	WLP-5-03	Number of Pins	5
Pcs/Reel	3,000	Package Size(mm)	1.26 x 1.06 x 0.4
Package Dimensions [0.1MB] Taping Specifications [0.1MB] Package Power Dissipation [0.1MB] Perspective [0.1MB] Control Plan [0.1MB]

DATA SHEET

Technical Document

Quality Reports

FAQ

How does the GO function of DC/DC converters work? Does it work just like a regulator?

Torex regard the PWM/PFM automatic switch control function as Green Operation (GO) in the case of DC/DC. The GO function is defined as the switching operation between the PFM mode for a small output current and the PWM mode for a large output current. The PFM control method controls the output current by increasing and decreasing the fall time according to the output current while keeping a pulse width. The PWM control method controls the output current by adjusting the pulse width of the rise time, which keeps the rise/fall time interval constant and increases the efficiency at a heavy load. By switching between the PFM control for a small output current and the PWM control for a large output current, the quiescent current can be controlled for both of heavy and light loads.

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.

References