数据搜索系统,热门电子元器件搜索 |
|
LTC2926 数据表(PDF) 14 Page - Linear Technology |
|
LTC2926 数据表(HTML) 14 Page - Linear Technology |
14 / 28 page LTC2926 14 2926fa Status Output The output aspect of the STATUS/PGI pin allows the LTC2926 to control and communicate with external downstream circuits. The pin is driven internally by an N-channel MOSFET pull-down to GND and a 10µA pull- up to an internal charge pump. The pull-down keeps the STATUS/PGI pin low until MGATE, SGATE1 and SGATE2 are fully enhanced, and the remote sense switches are closed. The pull-down then shuts off, and STATUS/PGI pin rises, indicating to downstream monitors that the supplies are fully ramped up. The STATUS/PGI pin pulls low when the MGATE, SGATE1, SGATE2 or RSGATE pin is low, either because a fault has been latched, or because the ON pin is low. An internal charge pump rail at VCC + 5.5V sources the STATUS/PGI pull-up current. An external resistor may be added to create logic level voltages, or the pin may be used to enhance the gates of external N-channel MOSFET switches, if desired. Power Good Timeout The input aspect of the STATUS/PGI pin allows external downstream monitoring circuits to control the LTC2926 as shown in Figure 9. The power good timeout circuit discon- nects the supply generators if for any reason the voltage level of the STATUS/PGI pin is not high after the timeout period. During a ramp-up, the timeout circuit will trip if the internal pull-down on STATUS/PGI fails to release, which indicates that supply ramping was not completed in the time allotted. If supply ramping completes, any downstream circuits that pull down the STATUS/PGI pin after the timer duration also will trip the timeout circuit. A fault caused by a power good timeout has the same effect as a fault triggered by the FAULT pin: supplies are disconnected and the fault latch is set. The fault latch may be cleared as described in the Fault Input/Output section above. The power good timer duration is configured by a capacitor tied between PGTMR and GND. The pin’s 10µA current source ramps up the capacitor voltage when the ON pin is high, otherwise 4mA pulls PGTMR to GND. The capacitor, CPGTMR, required to configure the power good timeout duration, tPGTMR, is determined from: C At V PGTMR PGTMR = µ 10 123 • . If the power good timeout feature is not used, tie PGTMR to GND. Retry on Fault The LTC2926 continuously attempts to ramp up the supplies after a fault if the FAULT pin is tied to the ON pin. When the FAULT and ON pins go low together, the internal fault latch is set by the falling FAULT pin, and the fault latch is reset by the falling ON pin. A short internal delay of several microseconds guarantees triggering of fast pull-down circuits on the RSGATE, MGATE, SGATE1 and SGATE2 pins, which opens the remote sense switches and discon- nects the master and slave supplies before the fault latch is reset. If no external signal pulls down the FAULT pin, the internal 8.5µA pull-up current or an external pull-up resistor increases the ON (and FAULT) pin voltage above 0.6V, which arms the fault latch. A ramp-up begins when ON is above 1.23V. In applications where the LTC2926 is configured for fault retry, some details of the retry behavior are determined by the source and duration of the fault signal. When a fault is triggered by an external pull-down signal on the FAULT (and ON) pin, supply ramping will not restart until the low input ceases. When a power good fault is triggered by an external pull-down signal on the STATUS/PGI pin, supply ramping restarts immediately. If the low signal persists APPLICATIO S I FOR ATIO Figure 9. External Load Monitor Controlling LTC2926 via Power Good Input 2926 F09 LTC2926 FB1 GND PGTMR CPGTMR STATUS/PGI ON ON/OFF SGATE2 10 Ω Q2 SGATE1 10 Ω RFB1 RFA1 FB2 RFB2 RFA2 S1 RST V2 V1 TOL S2 RST GND 1.8V SOURCE Q1 1.8V SLAVE1 2.5V SOURCE 2.5V SLAVE2 LTC2904 LOAD VOLTAGE MONITOR (10% TOLERANCE) |
类似零件编号 - LTC2926 |
|
类似说明 - LTC2926 |
|
|
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 |