DIU6921

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DIU6921 • Rev. 1.1

3) The DCR of the inductor and the core loss at the switching frequency must be low enough to achieve the

desired efficiency requirement. It is desirable to choose an inductor with DCR < 50 mΩ to achieve good

overall efficiency.

External bootstrap cap

This capacitor provides the gate driver voltage for internal high-side MOSFET. A 100 nF low ESR ceramic

capacitor connected between the BS pin and SW pin is recommended.

Load transient considerations

The DIU6921 regulator IC integrates the compensation components to achieve good stability and fast

transient responses. In some applications, adding a 22 pF ceramic cap in parallel with R1 may further speed

up the load transient responses and is thus recommended for applications with large load transient.

Layout design

The layout design of the DIU6921 regulator is relatively simple. For the best efficiency and minimum noise

problems, place the following components close to the IC: CIN, L1, R1, and R2.

1) It is desirable to maximize the PCB copper area connected to the GND pin to achieve the best thermal and

noise performance. If the board space allows, a ground plane is highly desirable.

2) CIN must be close to IN and GND pins. The loop area formed by CIN and GND must be minimized.

3) The PCB copper area associated with the SW pin must be minimized to avoid the potential noise problem.

4) The components R1 and R2, and the trace connecting to the FB pin must NOT be adjacent to the SW net

on the PCB layout to avoid the noise problem.

5) If the system chip interfacing with the EN pin has a high impedance state at shutdown mode and the IN pin

is connected directly to a power source such as a Li-Ion battery, it is desirable to add a pull-down 1 MΩ

resistor between the EN and GND pins to prevent the noise from falsely turning on the regulator at

shutdown mode.