FAN6520AM

FAN6520AM Datasheet

FAN6520A Single Synchronous Buck PWM Controller

Part	Datasheet
FAN6520AM	FAN6520AM (pdf)

Related Parts	Information
FAN6520AIM	FAN6520AIM
FAN6520AIMX	FAN6520AIMX
FAN6520AMX	FAN6520AMX

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FAN6520A Single Synchronous Buck PWM Controller FAN6520A Single Synchronous Buck PWM Controller October 2006 • Output Range 0.8V to VIN 0.8V Internal Reference Over Line Voltage and Temperature • Drives N-Channel MOSFETs • Simple Single-Loop Control Design Voltage-Mode PWM Control • Fast Transient Response High-Bandwidth Error Amplifier Full 0% to 100% Duty Cycle • Lossless, Programmable, Over-Current Protection Uses Upper MOSFET’s RDS ON • Small Converter Size 300kHz Fixed-Frequency Oscillator Internal Soft-Start 8-Lead SOIC • Power Supplies for PC Subsystems and Peripherals • MCH, GTL, and AGP Supplies • Cable Modems, Set-Top Boxes, and DSL Modems • DSP, Memory • Low-Voltage Distributed Power Supplies The FAN6520A simplifies implementing a complete control and protection scheme for a DC-DC stepdown converter. Designed to drive N-channel MOSFETs in a synchro-nous buck topology, the FAN6520A integrates the control, output adjustment, monitoring, and protection functions into a single 8-lead package. The FAN6520A employs a single feedback loop and voltage-mode control with fast transient response. The output voltage can be precisely regulated to as low as 0.8V, with a maximum tolerance of over-temperature and line-voltage variations. A fixed-frequency oscillator reduces design complexity, while balancing typical application cost. The error amplifier features a 15MHz gainbandwidth product and an 8V/µs slew rate, which enables high converter bandwidth for fast transient performance. The resulting PWM duty cycles range from 0% to The IC monitors the drop across the upper MOSFET and inhibits PWM operation appropriately to protect against over-current conditions. This approach simplifies the implementation and improves efficiency by eliminating the need for a current sense resistor. The FAN6520A is rated for operation from 0° to +70°C, with the FAN6520AI rated from to +85°C. Ordering Information Part Number FAN6520AM FAN6520AMX FAN6520AIM FAN6520AIMX Temperature Range 0°C to 70°C 0°C to 70°C to 85°C to 85°C Package SOIC-8 SOIC-8 SOIC-8 SOIC-8 Packing Rails Tape and Reel Rails Tape and Reel FAN6520A Single Synchronous Buck PWM Controller Pin Configuration BOOT HDRV GND LDRV FAN6520A SW COMP/OCSET/SD FB VCC FAN6520AM 8-Pin SOIC Package Pin Definitions Pin # 1 2 3 4 5 6 7 Name BOOT Bootstrap Supply Input. Provides a boosted voltage to the high-side MOSFET driver. Connect to bootstrap capacitor, as shown in Figure HDRV High-Side Gate-Drive Output. Connect to the gate of the high-side power MOSFET s . This pin is monitored by the adaptive shoot-through protection circuitry to determine when the upper MOSFET has turned off. Ground. The signal and power ground for the IC. Tie this pin to the ground island/plane through the lowest impedance connection available. Connect directly to source of low-side MOSFET s . LDRV Low-Side Gate-Drive Output. Connect to the gate of the low-side power MOSFET s . This pin is monitored by the adaptive shoot-through protection circuitry to determine when the lower MOSFET has turned off. VCC. Provides bias power to the IC and the drive voltage for LDRV. Bypass with a ceramic capacitor as close to this pin as possible. Feedback. This pin is the inverting input of the internal error amplifier. Use this pin, in com- bination with the COMP/OCSET pin, to compensate the voltage-control feedback loop of the converter. COMP/ OCSET/SD Compensation / Over-Current Set Point / Shut Down. This is a multiplexed pin. During operation, the output of the error amplifier drives this pin. During a short period of time following power-on reset POR , this pin is used to determine the over-current threshold of the converter. Pulling COMP/OCSET to a level below 0.8V disables the controller. Disabling the controller causes the oscillator to stop, the HDRV and LDRV outputs to be held low, and the soft-start circuitry to restart. Switch Node Input. The SW pin provides return for the high-side bootstrapped driver, is a sense point for the adaptive shoot-through protection, and is used to monitor the drop across the upper MOSFET’s RDS ON for current limit. Connect as shown in Figure 2005 Fairchild Semiconductor Corporation FAN6520A Single Synchronous Buck PWM Controller VCC 5 CVCC ROCSET COMP/OCSET 7 FAN6520A 1 BOOT

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FAN6520A Single Synchronous Buck PWM Controller

FAN6520A Single Synchronous Buck PWM Controller

October 2006
• Output Range 0.8V to VIN 0.8V Internal Reference Over Line Voltage and Temperature
• Drives N-Channel MOSFETs
• Simple Single-Loop Control Design

Voltage-Mode PWM Control
• Fast Transient Response

High-Bandwidth Error Amplifier Full 0% to 100% Duty Cycle
• Lossless, Programmable, Over-Current Protection Uses Upper MOSFET’s RDS ON
• Small Converter Size 300kHz Fixed-Frequency Oscillator Internal Soft-Start 8-Lead SOIC
• Power Supplies for PC Subsystems and Peripherals
• MCH, GTL, and AGP Supplies
• Cable Modems, Set-Top Boxes, and DSL Modems
• DSP, Memory
• Low-Voltage Distributed Power Supplies

The FAN6520A simplifies implementing a complete control and protection scheme for a DC-DC stepdown converter. Designed to drive N-channel MOSFETs in a synchro-nous buck topology, the FAN6520A integrates the control, output adjustment, monitoring, and protection functions into a single 8-lead package.

The FAN6520A employs a single feedback loop and voltage-mode control with fast transient response. The output voltage can be precisely regulated to as low as 0.8V, with a maximum tolerance of over-temperature and line-voltage variations. A fixed-frequency oscillator reduces design complexity, while balancing typical application cost. The error amplifier features a 15MHz gainbandwidth product and an 8V/µs slew rate, which enables high converter bandwidth for fast transient performance. The resulting PWM duty cycles range from 0% to

The IC monitors the drop across the upper MOSFET and inhibits PWM operation appropriately to protect against over-current conditions. This approach simplifies the implementation and improves efficiency by eliminating the need for a current sense resistor.

The FAN6520A is rated for operation from 0° to +70°C, with the FAN6520AI rated from to +85°C.
Ordering Information

Part Number FAN6520AM FAN6520AMX FAN6520AIM FAN6520AIMX

Temperature Range 0°C to 70°C 0°C to 70°C to 85°C
to 85°C

Package SOIC-8 SOIC-8 SOIC-8 SOIC-8

Packing Rails

Tape and Reel Rails

Tape and Reel

FAN6520A Single Synchronous Buck PWM Controller

Pin Configuration

BOOT HDRV

GND LDRV

FAN6520A

SW COMP/OCSET/SD FB VCC

FAN6520AM 8-Pin SOIC Package

Pin Definitions

Pin # 1 2 3 4 5 6 7

Name

BOOT

Bootstrap Supply Input. Provides a boosted voltage to the high-side MOSFET driver. Connect to bootstrap capacitor, as shown in Figure

HDRV

High-Side Gate-Drive Output. Connect to the gate of the high-side power MOSFET s . This pin is monitored by the adaptive shoot-through protection circuitry to determine when the upper MOSFET has turned off.

Ground. The signal and power ground for the IC. Tie this pin to the ground island/plane through the lowest impedance connection available. Connect directly to source of low-side MOSFET s .

LDRV

Low-Side Gate-Drive Output. Connect to the gate of the low-side power MOSFET s . This pin is monitored by the adaptive shoot-through protection circuitry to determine when the lower MOSFET has turned off.

VCC. Provides bias power to the IC and the drive voltage for LDRV. Bypass with a ceramic capacitor as close to this pin as possible.

Feedback. This pin is the inverting input of the internal error amplifier. Use this pin, in com-
bination with the COMP/OCSET pin, to compensate the voltage-control feedback loop of
the converter.

COMP/ OCSET/SD

Compensation / Over-Current Set Point / Shut Down. This is a multiplexed pin. During operation, the output of the error amplifier drives this pin. During a short period of time following power-on reset POR , this pin is used to determine the over-current threshold of the converter. Pulling COMP/OCSET to a level below 0.8V disables the controller. Disabling the controller causes the oscillator to stop, the HDRV and LDRV outputs to be held low, and the soft-start circuitry to restart.

Switch Node Input. The SW pin provides return for the high-side bootstrapped driver, is a
sense point for the adaptive shoot-through protection, and is used to monitor the drop
across the upper MOSFET’s RDS ON for current limit. Connect as shown in Figure
2005 Fairchild Semiconductor Corporation

FAN6520A Single Synchronous Buck PWM Controller

VCC 5

CVCC ROCSET

COMP/OCSET 7

FAN6520A
1 BOOT

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Datasheet ID: FAN6520AM 513955