数据搜索系统,热门电子元器件搜索 |
|
LTC1487 数据表(PDF) 8 Page - Linear Technology |
|
LTC1487 数据表(HTML) 8 Page - Linear Technology |
8 / 8 page 8 LTC1487 sn1487 1487fs APPLICATIO S I FOR ATIO effects of noise on the line signals. If the line is terminated or the receiver inputs are shorted together, the receiver output will retain the last valid line signal due to the 45mV of hysteresis incorporated in the receiver circuit. If the LTC1487 transceiver inputs are left floating (unterminated), an internal pull-up of 10 µA at the A input will force the receiver output to a known high state. Low Power Operation The LTC1487 draws very little supply current whenever the driver outputs are disabled. In shutdown mode, the quiescent current is typically less than 1 µA. With the receiver active and the driver outputs disabled, the LTC1487 will typically draw 80 µA quiescent current. With the driver outputs enabled but unterminated, quiescent current will rise slightly as one of the two outputs sources current into the internal receiver input resistance. With the minimum receiver input resistance of 70k and the maximum output swing of 5V, the quiescent current will rise by a maximum of 72 µA. Typical quiescent current rise with the driver enabled is about 40 µA. The quiescent current rises significantly if the driver is enabled when it is externally terminated. With 1/2 termination load (120 Ω between the driver outputs), the quiescent current will jump to at least 13mA as the drivers force a minimum of 1.5V across the termination resistance. With a fully terminated 60 Ω line attached, the current will rise to greater than 25mA with the driver enabled, completely overshadowing the extra 40 µA drawn by the internal receiver inputs. Shutdown Mode Both the receiver output (RO) and the driver outputs (A, B) can be placed in three-state mode by bringing RE HIGH and DE LOW respectively. In addition, the LTC1487 will enter shutdown mode when RE is HIGH and DE is LOW. In shutdown the LTC1487 typically draws only 1 µA of supply current. In order to guarantee that the part goes into shutdown, RE must be HIGH and DE must be LOW for at least 600ns simultaneously. If this time duration is less than 50ns the part will not enter shutdown mode. Toggling either RE or DE will wake the LTC1487 back up within 3.5 µs. If the driver is active immediately prior to shutdown, the supply current will not drop to 1 µA until the driver outputs have reached a steady state; this can take as long as 2.6 µs under worst case conditions. If the driver is disabled prior to shutdown the supply current will drop to 1 µA immediately. Slew Rate and Propagation Delay Many digital encoding schemes are dependent upon the difference in the propagation delay times of the driver and receiver. Figure 11 shows the test circuit for the LTC1487 propagation delay. Figure 11. Receiver Propagation Delay Test Circuit D BR R RECEIVER OUT R 100 Ω 100pF 100pF TTL IN tr, tf < 6ns LTC1487 • F11 The receiver delay times are: tPLH – tPHL = 13ns Typ, VCC = 5V The LTC1487 drivers feature controlled slew rate to reduce system EMI and improve signal fidelity by reducing reflec- tions due to misterminated cables. The driver’s skew times are: Skew = 250ns Typ, VCC = 5V 600ns Max, VCC = 5V, TA = – 40°C to 85°C For package descriptions consult the 1994 Linear Databook Volume III. PACKAGE DESCRIPTION ©LINEAR TECHNOLOGY CORPORATION 1995 LT/GP 0395 10K • PRINTED IN THE USA Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7487 (408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977 |
类似零件编号 - LTC1487 |
|
类似说明 - LTC1487 |
|
|
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 |