数据搜索系统,热门电子元器件搜索 |
|
SS23 数据表(PDF) 7 Page - Monolithic Power Systems |
|
SS23 数据表(HTML) 7 Page - Monolithic Power Systems |
7 / 10 page MP1580 – 2A, 380KHz STEP-DOWN CONVERTER MP1580 Rev. 3.0 www.MonolithicPower.com 7 12/5/2005 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2005 MPS. All Rights Reserved. TM Compensation The system stability is controlled through the COMP pin. COMP is the output of the internal transconductance error amplifier. A series capacitor-resistor combination sets a pole-zero combination to control the characteristics of the control system. The DC loop gain is: OUT FB VEA CS LOAD VDC V V A G R A × × × = Where AVEA is the transconductance error amplifier voltage gain, 400 V/V, GCS is the current sense gain, (roughly the output current divided by the voltage at COMP), 1.95 A/V and RLOAD is the load resistance (VOUT / IOUT where IOUT is the output load current). The system has 2 poles of importance, one is due to the compensation capacitor (C3), and the other is due to the output capacitor (C2). These are: VEA EA 1 P A 3 C 2 G f × × π = Where P1 is the first pole and GEA is the error amplifier transconductance (770µA/V). and LOAD 2 P R 2 C 2 1 f × × π = The system has one zero of importance, due to the compensation capacitor (C3) and the compensation resistor (R3). The zero is: 3 R 3 C 2 1 f 1 Z × × π = If a large value capacitor (C2) with relatively high equivalent-series-resistance (ESR) is used, the zero due to the capacitance and ESR of the output capacitor can be compensated by a third pole set by R3 and C6. The pole is: 3 R 6 C 2 1 f 3 P × × π = The system crossover frequency (the frequency where the loop gain drops to 1, or 0dB) is important. A good rule of thumb is to set the crossover frequency to approximately 1/10 of the switching frequency. In this case, the switching frequency is 380KHz, so use a crossover frequency, fC, of 40KHz. Lower crossover frequencies result in slower response and worse transient load recovery. Higher crossover frequencies can result in instability. Choosing the Compensation Components The values of the compensation components given in Table 4 yield a stable control loop for the output voltage and capacitor given. Table 4—Compensation Values for Typical Output Voltage/Capacitor Combinations VOUT C2 R3 C3 C6 2.5V 22µF Ceramic 7.5kΩ 2.2nF None 3.3V 22µF Ceramic 10kΩ 2nF None 5V 22µF Ceramic 15kΩ 1.2nF None 12V 22µF Ceramic 33kΩ 1nF None 2.5V 560µF/6.3V (30mΩ ESR) 200kΩ 1nF 100pF 3.3V 560µF/6.3V (30mΩ ESR) 200kΩ 1nF 82pF 5V 470µF/10V (30mΩ ESR) 250kΩ 1nF 56pF 12V 220µF/25V (30mΩ ESR) 250kΩ 1nF 27pF To optimize the compensation components for conditions not listed in Table 4, use the following procedure: Choose the compensation resistor to set the desired crossover frequency. Determine the value by the following equation: FB OUT CS EA C V V G G f 2 C 2 3 R × × × × π = Putting in the known constants and setting the crossover frequency to the desired 40KHz: OUT 8 V 2 C 10 37 . 1 3 R × × × ≈ Choose the compensation capacitor to set the zero below ¼ of the crossover frequency. Determine the value by the following equation: 3 R V 2 C 22 . 0 3 C OUT × × > |
类似零件编号 - SS23 |
|
类似说明 - SS23 |
|
|
链接网址 |
隐私政策 |
ALLDATASHEETCN.COM |
ALLDATASHEET是否为您带来帮助? [ DONATE ] |
关于 Alldatasheet | 广告服务 | 联系我们 | 隐私政策 | 链接交换 | 制造商名单 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 |