FP6276B-500kHz 6A High Efficiency Synchronous PWM Boost Converter에 대한 고찰

 

 

 

오늘은 FP6276B-500kHz 6A High Efficiency Synchronous PWM Boost Converter에 대한 고찰을 해 보겠습니다.

FP6276B는 Syn-Boost Converter로서 아래와 같은 특성을 지니고 있습니다.

 

내부 Switching Current가 6A로서, 1Cell Li-Ion Battery 입력을 사용해서 5V/2.4A까지는 충분히 출력을 내는 IC입니다.

요즘 많이 사용하는 1cell Battery System인 경우에 주변 부품이 적어서 사용하기 편리합니다. 

 

 

The FP6276B is a current mode boost DC-DC converter with PWM/PSM control. Its PWM circuitry with built-in 40mΩ high side switch and 40mΩ low side switch make this regulator highly power efficient. 

The internal compensation network also minimizes external component counts to only 6. 

An internal 0.6V voltage is connected to error amplifier the non-inverting input as precision reference voltage. 

Built-in soft-start function can reduce the inrush current.

 

• Current mode with PWM/PSM control

• Input voltage range: 2.4V~4.5V

• Adjustable Output up to 5.3V

• Shutdown current: <1uA

• Oscillator frequency: 500KHz

• Reference voltage: 0.6V +/-2%

• Disconnect load during shutdown

• Cycle-by-cycle current limit

• Low RDS(on): 40mΩ for both high and low side

• Protection: OTP, OCP, SCP

• Internal compensation

• Internal soft-start: 7ms

• Package: SOP-8L(EP)

 

Function Description

Operation
The FP6276B is a current mode synchronous boost converter. The constant switching frequency
is 500 kHz and operates with pulse width modulation (PWM). 

Build-in 40mΩ high side switch and 40mΩ low side switch provides a high efficient conversion.

 

Soft Start Function
Soft start circuitry is integrated into FP6276B to avoid inrush current during power on. 

After the IC is enabled, the output of error amplifier is clamped by the internal soft-start function, which causes
PWM pulse width increasing slowly and thus reducing input surge current.

 

Current Limit Program (OCP)
A resistor between OC and GND pin programs peak switch current. The resistor value should be
between 37.5k and 300k. The current limit can be set from 5 A to 0.8A. Keep traces at this pin as short
as possible. Do not put capacitance at this pin.

 

Over Temperature Protection (OTP)
FP6276B will turn off the power MOSFET automatically when the internal junction temperature is
higher than 150°C. 

The power MOSFET wake up when the junction temperature drops 30°C under the OTP threshold temperature.

 

 

 

Application Information

Inductor Selection
Inductance value is decided based on different condition. 1.5uH to 4.7μH inductor value is recommended for

general application circuit. There are three important inductor specifications,

DC resistance, saturation current and core loss. Low DC resistance has better power efficiency.

Also, avoid inductor saturation which will cause circuit system unstable and lower core loss at 500KHz.

 

Capacitor Selection
The output capacitor is required to maintain the VO DC voltage. 

Low ESR capacitors are preferred to reduce the output voltage ripple. 

Ceramic capacitor of X5R and X7R are recommended, which have low equivalent series resistance (ESR) 

and wider operation temperature range.

 

Output Voltage Programming
The output voltage is set by a resistive voltage divider from the output voltage to FB.

 

 

아래사진은 Input=3.6V, Output=5V/2.4A Demo Board입니다.

 

 

 

 

아래는 spec sheet의 응용 회로도입니다.

 

 

 

Suggested PCB Artwork Layout

 

아래는 PCB Artwork할때, Layout을 고려해야하는부분을 나열하였습니다.

 

 
1. The power traces, consisting of the GND trace, the LX trace and the VIN trace should be kept short, direct and wide. 
2. Layout LX switching node wide and short trace to reduce EMI. 
3. Place C1 near VIN pin as closely as possible to maintain input voltage steady and filter out the pulsing input current. 
4. The resistive divider R1 and R2 must be connected to FB pin directly and as closely as possible. 
5. FB is a sensitive node. Please keep it away from switching node LX. 
6. The GND of the IC, C1, C3 and C4 should be connected close together directly to a power ground plane.

7. Use ceramic capacitor of X5R or X7R for C1 and C2.
8. R4 and C5 are added for reducing EMI (Electromagnetic Interference).
9. EN voltage must be less than or equal to VIN voltage.

 

 

FP6276BV069-G1.pdf

0.68MB