Datasheet LT8300 (Analog Devices) - 10
| Fabricante | Analog Devices |
| Descripción | 100VIN Micropower Isolated Flyback Converter with 150V/260mA Switch |
| Páginas / Página | 24 / 10 — APPLICATIONS INFORMATION. Figure 1. Output Power for 3.3V Output. … |
| Revisión | A |
| Formato / tamaño de archivo | PDF / 1.4 Mb |
| Idioma del documento | Inglés |
APPLICATIONS INFORMATION. Figure 1. Output Power for 3.3V Output. Figure 2. Output Power for 5V Output
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LT8300
APPLICATIONS INFORMATION
3.5 3.5 MAXIMUM MAXIMUM 3.0 OUTPUT 3.0 OUTPUT N = 12:1 POWER POWER N = 8:1 N = 6:1 2.5 2.5 N = 8:1 2.0 N = 6:1 2.0 N = 4:1 1.5 N = 4:1 1.5 N = 2:1 OUTPUT POWER (W) 1.0 OUTPUT POWER (W) 1.0 0.5 0.5 0 0 0 20 40 60 80 100 0 20 40 60 80 100 INPUT VOLTAGE (V) INPUT VOLTAGE (V) 8300 F01 8300 F02
Figure 1. Output Power for 3.3V Output Figure 2. Output Power for 5V Output
3.5 3.5 N = 4:1 N = 2:1 3.0 3.0 MAXIMUM N = 3:1 N = 3:2 MAXIMUM 2.5 OUTPUT 2.5 POWER OUTPUT N = 2:1 POWER N = 1:1 2.0 2.0 1.5 1.5 N = 1:1 N = 1:2 OUTPUT POWER (W) 1.0 OUTPUT POWER (W) 1.0 0.5 0.5 0 0 0 20 40 60 80 100 0 20 40 60 80 100 INPUT VOLTAGE (V) INPUT VOLTAGE (V) 8300 F03 8300 F04
Figure 3. Output Power for 12V Output Figure 4. Output Power for 24V Output Primary Inductance Requirement
In addition to the primary inductance requirement for The LT8300 obtains output voltage information from the the minimum switch-off time, the LT8300 has minimum reflected output voltage on the SW pin. The conduction of switch-on time that prevents the chip from turning on secondary current reflects the output voltage on the pri- the power switch shorter than approximately 160ns. mary SW pin. The sample-and-hold error amplifier needs This minimum switch-on time is mainly for leading-edge a minimum 350ns to settle and sample the reflected out- blanking the initial switch turn-on current spike. If the put voltage. In order to ensure proper sampling, the sec- inductor current exceeds the desired current limit during ondary winding needs to conduct current for a minimum that time, oscillation may occur at the output as the cur- of 350ns. The following equation gives the minimum rent control loop will lose its ability to regulate. Therefore, value for primary-side magnetizing inductance: the following equation relating to maximum input voltage must also be followed in selecting primary-side magnetiz- t ( ) ing inductance: L OFF(MIN) • N PS • VOUT + VF PRI ≥ t I SW(MIN) L ON(MIN) • VIN(MAX) PRI ≥ I t SW(MIN) OFF(MIN) = Minimum switch-off time = 350ns ISW(MIN) = Minimum switch current limit = 52mA tON(MIN) = Minimum Switch-On Time = 160ns Rev. A 10 For more information www.analog.com Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Operation Applications Information Typical Applications Package Description Typical Application Related Parts
APPLICATIONS INFORMATION
3.5 3.5 MAXIMUM MAXIMUM 3.0 OUTPUT 3.0 OUTPUT N = 12:1 POWER POWER N = 8:1 N = 6:1 2.5 2.5 N = 8:1 2.0 N = 6:1 2.0 N = 4:1 1.5 N = 4:1 1.5 N = 2:1 OUTPUT POWER (W) 1.0 OUTPUT POWER (W) 1.0 0.5 0.5 0 0 0 20 40 60 80 100 0 20 40 60 80 100 INPUT VOLTAGE (V) INPUT VOLTAGE (V) 8300 F01 8300 F02
Figure 1. Output Power for 3.3V Output Figure 2. Output Power for 5V Output
3.5 3.5 N = 4:1 N = 2:1 3.0 3.0 MAXIMUM N = 3:1 N = 3:2 MAXIMUM 2.5 OUTPUT 2.5 POWER OUTPUT N = 2:1 POWER N = 1:1 2.0 2.0 1.5 1.5 N = 1:1 N = 1:2 OUTPUT POWER (W) 1.0 OUTPUT POWER (W) 1.0 0.5 0.5 0 0 0 20 40 60 80 100 0 20 40 60 80 100 INPUT VOLTAGE (V) INPUT VOLTAGE (V) 8300 F03 8300 F04
Figure 3. Output Power for 12V Output Figure 4. Output Power for 24V Output Primary Inductance Requirement
In addition to the primary inductance requirement for The LT8300 obtains output voltage information from the the minimum switch-off time, the LT8300 has minimum reflected output voltage on the SW pin. The conduction of switch-on time that prevents the chip from turning on secondary current reflects the output voltage on the pri- the power switch shorter than approximately 160ns. mary SW pin. The sample-and-hold error amplifier needs This minimum switch-on time is mainly for leading-edge a minimum 350ns to settle and sample the reflected out- blanking the initial switch turn-on current spike. If the put voltage. In order to ensure proper sampling, the sec- inductor current exceeds the desired current limit during ondary winding needs to conduct current for a minimum that time, oscillation may occur at the output as the cur- of 350ns. The following equation gives the minimum rent control loop will lose its ability to regulate. Therefore, value for primary-side magnetizing inductance: the following equation relating to maximum input voltage must also be followed in selecting primary-side magnetiz- t ( ) ing inductance: L OFF(MIN) • N PS • VOUT + VF PRI ≥ t I SW(MIN) L ON(MIN) • VIN(MAX) PRI ≥ I t SW(MIN) OFF(MIN) = Minimum switch-off time = 350ns ISW(MIN) = Minimum switch current limit = 52mA tON(MIN) = Minimum Switch-On Time = 160ns Rev. A 10 For more information www.analog.com Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Operation Applications Information Typical Applications Package Description Typical Application Related Parts