Confidential

Datasheet Version 1.0

July

2015. Revision 1.0

MagnaChip Semiconductor Ltd.

6

Operation

The MAP7103 provided a regulated supply voltage for panel source driver ICs. The MAP7103 uses a constant

frequency, peak current mode PWM(Pulse Width Modulation) boost regulation architecture to regulate the

feedback voltage.

At the beginning of each cycle, the N-channel MOSFET switch is turned on, forcing the inductor current to rise.

The current at the source of the switch is internally measured and converted to a voltage by the current sense

amplifier. That voltage is compared to the error voltage at COMP. The voltage at the output of the error amplifier

is an amplified version of the difference between the 1.25V reference voltage and the feedback voltage voltage.

When these two voltage are equal, the PWM comparator turns off the switch forcing the inductor current to the

output capacitor through the external rectifier. This causes the inductor current to decrease. The peak inductor

current is controlled by the voltage at COMP, which in turn is controlled by the output voltage. Thus the output

voltage is regulated by the inductor current to satisfy the load. The use of current mode regulation improves

transient response and control loop stability.

Application Information

Soft-Start Capacitor

The MAP7103 provides soft-start function to minimize the inrush current at the input. This prevents faults tripping

of the input voltage at startup due to input current overshoot. When powered on, a 5uA internal constant current

charges an external capacitor at SS pin. As the SS capacitor is charged, the voltage at SS rises. The MAP7103

internally clamps the voltage at COMP to 700mV above the voltage at SS. The soft-start ends when the voltage

at SS reaches 1.25V. This limits the inductor current at startup, forcing the input current to rise slowly to the

current required to regulate the output voltage.

The soft-start period is determined by the equation :

Setting the Output Voltage

The regulated output voltage is shown as the following equation

The recommended voltage for R2 should be at

least 10kΩ

Selecting the input Capacitor

Lower ESR ceramic capacitor are recommended for input capacitor applications. Low ESR will reduce the

Input voltage ripple caused by switching operation. A 10uF capacitor is sufficient for most applications.

Selecting the Output Capacitor

The output capacitor is required to maintain the DC output voltage. Low ESR capacitor are preferred to keep

the output voltage ripple to a minimum. The characteristic of the output capacitor also affects the stability of the

regulation control system. The output voltage ripple is shown as the following equation: