LX1552MY

LX1552MY Datasheet

LX1552/3/4/5

Part	Datasheet
LX1552MY	LX1552MY (pdf)

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LX1553CM	LX1553CM
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LX1553MY	LX1553MY
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PDF Datasheet Preview
NOT RECOOBMSMOENLDEETDEFOPRRNOEDWUDECSTIGNS LX1552/3/4/5 ULTRA-LOW START-UP CURRENT, CURRENT-MODE PWM THE INFINITE POWER OF INNOVATION PRODUCTION DATA SHEET The LX155x family of ultra-low start-up current 250µA max , current mode control ICs offer new levels of energy efficiency for offline converter applications. They are ideally optimized for personal computer and CRT power supplies although they can be used in any number of off-line applications where energy efficiency is critical. Coupled with the fact that the LX155x series requires a minimal set of external components, the series offers an excellent value for cost conscious consumer applications. Optimizing energy efficiency, the LX155x series demonstrates a significant power reduction as compared with other similar off-line controllers. Table 1 compares the SG384x, UC384xA and the LX155x start-up resistor power dissipation. The LX155x offers an overall 4X reduction in power dissipation. Additionally, the precise oscillator discharge current gives the power supply designer considerable flexibility in optimizing system duty cycle consistency. The current mode architecture demonstrates improved load regulation, pulse by pulse current limiting and inherent protection of the power supply output switch. The LX155x includes a bandgap reference trimmed to 1%, an error amplifier, a current sense comparator internally clamped to 1V, a high current totem pole output stage for fast switching of power MOSFETs, and an externally programmable oscillator to set operating frequency and maximum duty cycle. The under voltage lock-out circuitry is designed to operate with as little as 250µA of supply current permitting very efficient bootstrap designs. IMPORTANT For the most current data, consult MICROSEMI’s website: KEY FEATURES - Ultra-Low Start-up Current 150µA Typical - Trimmed Oscillator Discharge Current ±2% Typical - Initial Oscillator Frequency Better Than ±4% - Output Pulldown During UVLO - Precision 2.5V Reference ±2 maximum - Current Sense Delay to Output 150ns Typical - Automatic Feed Forward Compensation - Pulse-by-Pulse Current Limiting - Enhanced Load response Characteristics - Under-Voltage Lockout with Hysteresis - Double Pulse Suppression - High Current Totem Pole Output ±1A Peak - 500KHz Operation PRODUCT HIGHLIGHT Typical Application of LX155x Using Its MicroPower Start-Up Feature AC INPUT I ST VCC LX1552 LX1554 Design Using Max. Start-up Current Specification IST Typical Start-up Resistor Value RST Max. Start-up Resistor Power Dissipation PR SG384x 1000µA 2.26W UC384xA 500µA 1.13W LX155x 250µA 0.56W Note Calculation is done for universal AC input specification of VACMIN = 90VRMS to VACMAX = 256VRMS using the following equation resistor current is selected to be 2 * IST VACMIN

PDF Datasheet Preview

NOT RECOOBMSMOENLDEETDEFOPRRNOEDWUDECSTIGNS

LX1552/3/4/5

ULTRA-LOW START-UP CURRENT, CURRENT-MODE PWM

THE INFINITE POWER OF INNOVATION

PRODUCTION DATA SHEET

The LX155x family of ultra-low start-up current 250µA max , current mode control ICs offer new levels of energy efficiency for offline converter applications. They are ideally optimized for personal computer and CRT power supplies although they can be used in any number of off-line applications where energy efficiency is critical. Coupled with the fact that the LX155x series requires a minimal set of external components, the series offers an excellent value for cost conscious consumer applications.

Optimizing energy efficiency, the LX155x series demonstrates a significant power reduction as compared with other similar off-line controllers. Table 1 compares the SG384x, UC384xA and the LX155x start-up resistor power dissipation. The LX155x offers an overall 4X reduction in power dissipation.

Additionally, the precise oscillator discharge current gives the power supply designer considerable flexibility in optimizing system duty cycle consistency.

The current mode architecture demonstrates improved load regulation, pulse by pulse current limiting and inherent protection of the power supply output switch. The LX155x includes a bandgap reference trimmed to 1%, an error amplifier, a current sense comparator internally clamped to 1V, a high current totem pole output stage for fast switching of power MOSFETs, and an externally programmable oscillator to set operating frequency and maximum duty cycle. The under voltage lock-out circuitry is designed to operate with as little as 250µA of supply current permitting very efficient bootstrap designs.

IMPORTANT For the most current data, consult MICROSEMI’s website:

KEY FEATURES
- Ultra-Low Start-up Current 150µA

Typical
- Trimmed Oscillator Discharge

Current ±2% Typical
- Initial Oscillator Frequency Better

Than ±4%
- Output Pulldown During UVLO - Precision 2.5V Reference ±2
maximum
- Current Sense Delay to Output
150ns Typical
- Automatic Feed Forward

Compensation
- Pulse-by-Pulse Current Limiting - Enhanced Load response

Characteristics
- Under-Voltage Lockout with

Hysteresis
- Double Pulse Suppression - High Current Totem Pole Output
±1A Peak
- 500KHz Operation

PRODUCT HIGHLIGHT

Typical Application of LX155x Using Its MicroPower Start-Up Feature

AC INPUT

I ST VCC

LX1552

LX1554

Design Using Max. Start-up Current Specification IST Typical Start-up Resistor Value RST Max. Start-up Resistor Power Dissipation PR

SG384x 1000µA 2.26W

UC384xA 500µA 1.13W

LX155x 250µA 0.56W

Note Calculation is done for universal AC input specification of VACMIN = 90VRMS to VACMAX = 256VRMS using the following equation resistor current is selected to be 2 * IST VACMIN

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Datasheet ID: LX1552MY 649001