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MA2003

Major Power Technology Co., Ltd.

Rev.1.0

Oct.11, 2014



FUNCTION DESCRIPTION

Setting the Output Voltage

Application circuit item shows the basic application circuit with MA2003 adjustable

output version. The external resistor sets the output voltage according to the following

equation:

)

R1

R2

(1

1.238V x

OUT

V





Table 1—Resistor Selection for Common Output Voltages

R1 (kΩ)

R2 (kΩ)

12

54

470

16

39

470

24

39

720

27

36

750

For most applications, R2 is a suggested a value by 300K~850KΩ. Place the

resistor-divider as close to the IC as possible to reduce the noise sensitivity.

Under Voltage Lockout (UVLO)

To avoid mis-operation of the device at low input voltages an under voltage lockout is

included that disables the device, if the input voltage falls below (2.25V-200mV).

Input Capacitor Selection

The input capacitor reduces the surge current drawn from the input and switching

noise from the device. The input capacitor impedance at the switching frequency shall be

less than input source impedance to prevent high frequency switching current passing to the

input. A low ESR input capacitor sized for maximum RMS current must be used. Ceramic

capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR

and small temperature coefficients. A 4.7µF ceramic capacitor for most applications is

sufficient. For a lower output power requirement application, this value can be decreased.

Output Capacitor Selection

The output capacitor is required to keep the output voltage ripple small and to ensure

regulation loop stability. The output capacitor must have low impedance at the switching

frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended due to their

low ESR and high ripple current. A 2.2uF ceramic capacitors works for most of the

applications. Higher capacitor values can be used to improve the load transient response.