HM9228 datasheet(4/10 Pages) HMSEMI

4 / 10 page

SLOPE

OTP

UVLO

OCP

CMP

Current AMP

OSC/600KHz

Control

Logic

Current AMP

Bandgap

reference

1.24V

AGND

PGND

AVDD

PVDD

HM9228

Figure 4. Functional Block Diagram

FUNCTIONAL DESCRIPTION

NORMAL OPERATION

The boost converter is designed for output

voltage up to 24V with a 12A/24V power MOSFET.

The low

dson

of the internal power switches

enables better power efficiency. The chip, which

operates in a current mode scheme with constant

frequency 600KHz. It operates with Pulse With

Modulation(PWM). To avoid

the inrush current

during power up, soft start circuit is integrated in the

chip.

The controller circuit of the device is based on a

fixed frequency multiple feedback controller

topology. Input voltage, output voltage, and voltage

drop on the NMOS switch are monitored and

feedback to the regulator. So changes in the

operating conditions of the converter directly affect

the duty cycle and must not take the indirect and

slow way through the control loop and the error

amplifier. The control loop, determined by the error

amplifier, only has to handle small signal errors.

The input for it is the feedback voltage on the FB

pin, the voltage on the internal resistor divider. It is

compared with the internal reference voltage to

generate an accurate and stable output voltage.

CYCLE BY CYCLE CURRENT LIMIT

The peak current of the NMOS switch is also

sensed to limit the maximum current flowing

through the switch and the inductor. The typical

peak current limit is set to exceed 12A.

UNDERVOLTAGE LOCKOUT (UVLO)

Under voltage lockout prevents operation of the

device at input voltages below typical 2.6V when

the input voltage is falling. When the input voltage is

below the under voltage threshold, the device is

shut down and the internal switch FETs are turned

off. If the input voltage rises by under voltage

lockout hysteresis(3.2V), the IC restarts.

HM9228

_____________________________

_________

HM9228 Datasheet(PDF) 4 Page - Shenzhen Huazhimei Semiconductor Co., Ltd

HM9228 Datasheet(HTML) 4 Page - Shenzhen Huazhimei Semiconductor Co., Ltd

Html Pages

1 2 3 4 5 6 7 8 9 10

Datasheet Download

Link URL