データシートサーチシステム |
|
FAN1582D25X データシート(PDF) 6 Page - Fairchild Semiconductor |
|
FAN1582D25X データシート(HTML) 6 Page - Fairchild Semiconductor |
6 / 11 page FAN1582 PRODUCT SPECIFICATION 6 REV. 1.1.3 11/9/03 General The FAN1582, FAN1582-1.5, and FAN1582-2.5 are three- terminal regulators optimized for GTL+ VTT termination and logic applications. These devices are short-circuit protected, and offer thermal shutdown to turn off the regulator when the junction temperature exceeds about 150°C. The FAN1582 series provides low dropout voltage and fast transient response. Frequency compensation uses capacitors with low ESR while still maintaining stability. This is critical in addressing the needs of low voltage high speed microproces- sor buses like GTL+. VIN and VCNTL Functions The FAN1582 utilizes a dual supply approach to maximize efficiency. The collector of the power device is brought out to the VIN pin to minimize internal power dissipation under high current loads. VCNTL provides power for the control circuitry and the drive for the output NPN transistor. VCNTL should be at least 1.2 V higher than the output voltage. Special care was taken to ensure there are no supply- sequencing problems. The output voltage will not turn on until both supplies are operating. If the control voltage comes up first, the output current will be typically limited to about 3.0 mA until the power input voltage comes up. If the power input voltage comes up first the output will not turn on at all until the control voltage comes up. The output can never come up unregulated. The FAN1582 can also be used as a single supply device with the control and power inputs tied together. In this mode, the dropout is determined by the minimum control voltage. Stability The FAN1582 series requires an output capacitor as a part of the frequency compensation. It is recommended to use a 22µF solid tantalum or a 100µF aluminum electrolytic on the output to ensure stability. The frequency compensation of these devices optimizes the frequency response with low ESR capaci- tors. In general, it is suggested to use capacitors with an ESR of <0.3 Ω. It is also recommended to use bypass capacitors such as a 22µF tantalum or a 100µF aluminum on the adjust pin of the FAN1582 for low ripple and fast transient response. When these bypassing capacitors are not used at the adjust pin, smaller values of output capacitors provide equally good results. A graph showing stability of output capacitance ESR vs load current can be found under Typical Performance Characteristics. Protection Diodes In normal operation, the FAN1582 series does not require any protection diodes. For the FAN1582, internal resistors limit internal current paths on the adjust pin. Therefore, even with bypass capacitors on the adjust pin, no protection diode is needed to ensure device safety under short-circuit conditions. A protection diode between the input and output pins is usu- ally not needed. An internal diode between the input and the output pins on the FAN1582 series can handle microsecond surge currents of 50A to 100A. Even with large value output capacitors it is difficult to obtain those values of surge currents in normal operation. Only with large values of out- put capacitance, such as 1000µF to 5000µF, and with the input pin instantaneously shorted to ground can damage occur. A crowbar circuit at the input can generate those levels of current; a diode from output to input is then recommended, as shown in Figure 1. Usually, normal power supply cycling or system “hot plugging and unplugging” will not generate current large enough to do any damage. Figure 1. Optional Protection Diode Ripple Rejection In applications that require improved ripple rejection, a bypass capacitor from the adjust pin of the FAN1582 to ground reduces the output ripple by the ratio of VOUT/1.25V. The impedance of the adjust pin capacitor at the ripple frequency should be less than the value of R1 (typically in the range of 100 Ω to 120Ω) in the feedback divider network in Figure 1. Therefore, the value of the required adjust pin capacitor is a function of the input ripple frequency. For example, if R1 equals 100 Ω and the ripple frequency equals 120Hz, the adjust pin capacitor should be 22µF. At 10kHz, only 0.22µF is needed. Output Voltage The FAN1582 regulator develops a 1.25V reference voltage between the output pin and the adjust pin (see Figure 2). Placing a resistor R1 between these two terminals causes a constant current to flow through R1 and down through R2 to set the overall output voltage. Normally, this current is the specified minimum load current of 10mA. FAN1582 Adj C2 22 µF VOUT + C1 10 µF + CADJ + Vcntl Vsense Vin Vout R1 R2 D1 1N4002 (OPTIONAL) VIN VOUT FAN1582–1.5, 2.5 Gnd C2 22 µF VOUT + C1 10 µF + Vcntl Vsense Vin Vout D1 1N4002 (OPTIONAL) VIN VCNTL |
同様の部品番号 - FAN1582D25X |
|
同様の説明 - FAN1582D25X |
|
|
リンク URL |
プライバシーポリシー |
ALLDATASHEET.JP |
ALLDATASHEETはお客様のビジネスに役立ちますか? [ DONATE ] |
Alldatasheetは | 広告 | お問い合わせ | プライバシーポリシー | リンク交換 | メーカーリスト All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |