поискавой системы для электроныых деталей |
|
LM337BD2TG датащи(PDF) 7 Page - ON Semiconductor |
|
LM337BD2TG датащи(HTML) 7 Page - ON Semiconductor |
7 / 10 page LM337 http://onsemi.com 7 APPLICATIONS INFORMATION Basic Circuit Operation The LM337 is a 3−terminal floating regulator. In operation, the LM337 develops and maintains a nominal −1.25 V reference (Vref) between its output and adjustment terminals. This reference voltage is converted to a programming current (IPROG) by R1 (see Figure 17), and this constant current flows through R2 from ground. The regulated output voltage is given by: Vout + Vref 1 ) R 2 R 1 ) I Adj R 2 Since the current into the adjustment terminal (IAdj) represents an error term in the equation, the LM337 was designed to control IAdj to less than 100 mA and keep it constant. To do this, all quiescent operating current is returned to the output terminal. This imposes the requirement for a minimum load current. If the load current is less than this minimum, the output voltage will rise. Since the LM337 is a floating regulator, it is only the voltage differential across the circuit which is important to performance, and operation at high voltages with respect to ground is possible. Figure 17. Basic Circuit Configuration + - Vout CO R2 IPROG R1 Adjust Vin LM337 Vout + Vref = -1.25 V Typical Vref Vout IAdj Load Regulation The LM337 is capable of providing extremely good load regulation, but a few precautions are needed to obtain maximum performance. For best performance, the programming resistor (R1) should be connected as close to the regulator as possible to minimize line drops which effectively appear in series with the reference, thereby degrading regulation. The ground end of R2 can be returned near the load ground to provide remote ground sensing and improve load regulation. External Capacitors A 1.0 mF tantalum input bypass capacitor (Cin) is recommended to reduce the sensitivity to input line impedance. The adjustment terminal may be bypassed to ground to improve ripple rejection. This capacitor (CAdj) prevents ripple from being amplified as the output voltage is increased. A 10 mF capacitor should improve ripple rejection about 15 dB at 120 Hz in a 10 V application. An output capacitance (CO) in the form of a 1.0 mF tantalum or 10 mF aluminum electrolytic capacitor is required for stability. Protection Diodes When external capacitors are used with any IC regulator it is sometimes necessary to add protection diodes to prevent the capacitors from discharging through low current points into the regulator. Figure 18 shows the LM337 with the recommended protection diodes for output voltages in excess of −25 V or high capacitance values (CO > 25 mF, CAdj > 10 mF). Diode D1 prevents CO from discharging thru the IC during an input short circuit. Diode D2 protects against capacitor CAdj discharging through the IC during an output short circuit. The combination of diodes D1 and D2 prevents CAdj from the discharging through the IC during an input short circuit. Figure 18. Voltage Regulator with Protection Diodes + - + Cin -Vin R2 CAdj + + 1N4002 LM337 Vout Vout Vin D1 1N4002 R1 D2 CO Adjust Vout Figure 19. D2PAK Thermal Resistance and Maximum Power Dissipation versus P.C.B. Copper Length 30 40 50 60 70 80 Minimum Size Pad 2.0 oz. Copper L L Free Air Mounted Vertically RqJA 1.0 1.5 2.0 2.5 3.0 3.5 010 20 30 25 15 5.0 L, LENGTH OF COPPER (mm) PD(max) for TA = +50°C |
Аналогичный номер детали - LM337BD2TG |
|
Аналогичное описание - LM337BD2TG |
|
|
ссылки URL |
Конфиденциальность |
ALLDATASHEETRU.COM |
Вашему бизинису помогли Аллдатащит? [ DONATE ] |
Что такое Аллдатащит | реклама | контакт | Конфиденциальность | обмен ссыками | поиск по производителю 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 |