2 Channel 5.5V 1.5A 1.5MHz DC-DC Step down PMU

Current Limiting

A current limit feature protects the device and any external components during overload conditions. In PWM mode

the current limiting is implemented by using an internal comparator that trips at current levels according to the buck

capability. If the output is shorted to ground the device enters a timed current limit mode where the NFET is turned

on for a longer duration until the inductor current falls below a low threshold, ensuring inductor current has more

time to decay, thereby preventing runaway.

Under Voltage Lock Out (UVLO)

The VIN voltage is monitored for a supply under voltage condition, for which the operation of the device cannot be

guaranteed. The part will automatically disable PMIC. To prevent unstable operation, the UVLO has a hysteresis

window. An under voltage lockout (UVLO) will disable BUCKs outputs, Once the supply voltage is above the

UVLO hysteresis, the device will initiate a power-up sequence and then enter the active state.

Over Voltage Lock Out (OVLO)

The VIN voltage is monitored for a supply over voltage condition, for which the operation of the device cannot be

guaranteed. The purpose of OVLO is to protect the part and all other components connected to the PMIC outputs

from any damage and malfunction. Once VIN rises over about 6.5V, BUCKs will be disabled automatically. To

prevent unstable operation, the OVLO has a hysteresis window. An over voltage lockout (OVLO) will force the

device into the reset state, Once the supply voltage goes below the OVLO lower threshold, the device will initiate

a power-up sequence and then enter the active state.

Thermal Shutdown (OTP)

The temperature of the silicon die is monitored for an over-temperature condition, for which the operation of the

device cannot be guaranteed. The part will automatically be disabled if the temperature is too high. The thermal

shutdown (OTP) will force the device into the reset state. In reset, all circuitry is disabled. To prevent unstable

operation, the OTP has a hysteresis window of about 20°C. Once the temperature has decreased below the OTP

hysteresis, the device will initiate a power-up sequence and then enter the active state. In the active state, the part

will start up as if for the first time.

Detailed Design Procedure

HM5213 require an input capacitor, an output capacitor and an inductor. These components are critical to the

performance of the device. HM5213 are internally compensated and do not require external components to achieve

stable operation. The output voltage can be programmed by resistor divider.

����1 + ����2

����2

Select R1 value around 50kΩ

����2 = ����1 ×

Output Inductors and Capacitors Selection

There are several design considerations related to the selection of output inductors and capacitors:

•

Load transient response

R1

R2

HM5213