DS2148 ； DS21348 点击型号即可查看芯片规格书
本应用说明描述了Maxim的DS2148和DS21348 (E1/T1/J1线路接口单元)作为T1或E1操作的中继器的寄存器设置。这可以用硬件或软件模式的设备来完成。
这两个liu的接收灵敏度是可编程的，对于T1应用可高达-36dB，对于E1应用可高达-43dB。
为了简化设计，建议使用2.048MHz振荡器，并使用DS2148和DS21348的内部寄存器设置将T1应用的MCLK转换为1.544MHz。
图1所示、典型的T1/E1中继器应用
DS2148或DS21348在硬件模式下的配置设置如下:
| 硬件模式设置T1 | E1的硬件模式设置 |
| MCLK = 2.048MHz | MCLK = 2.048MHz |
| Bis1 = 1 bis0 = 1 | Bis1 = 1 bis0 = 1 |
| ce = 0 | ce = 0 |
| DJA = 0或1(应用程序依赖) | DJA = 0或1(应用程序依赖) |
| Hbe = 1 | Hbe = 1 |
| JAS = 0或1(应用程序依赖) | JAS = 0或1(应用程序依赖) |
| Nrze = 0 | Nrze = 0 |
| TPD = 0 | TPD = 0 |
| L2 = l1 = l0 = 0 | L2 / L1 / 10(应用程序依赖) |
| Tx1 = 0, tx0 = 0 | Tx1 = 0, tx0 = 0 |
| Loop1 = 0, loop0 = 0 | Loop1 = 0, loop0 = 0 |
| Egl = 1, ets = 1(有限长途) Egl = 0, ets = 1(长期) | Egl = 0, ets = 0(短时间) Egl = 1, ets = 0(长期) |
| Mm1 = 0 mm0 = 0 | Mm1 = 0 mm0 = 0 |
| RT1 = 1, RT0 = 0(内部Rx侧，100欧姆启用) | RT1 = 0, RT0 = 1(内部Rx侧，120欧姆 enabled) RT1 = 1, RT0 = 1(内部Rx侧，75欧姆 enabled) |
| Jamux = 1, ets = 1 | Jamux = 1, ets = 0 |
DS2148或DS21348在软件模式下的配置设置如下:
| 软件模式T1寄存器设置 | 软件模式E1的寄存器设置 | ||
| MCLK = 2.048MHz | MCLK = 2.048MHz | ||
| CCR1 (00 h) | Ccr1.7 = 1 Ccr1.6 = 0 Ccr1.3 = 1 Ccr1.1 = 1 | CCR1 (00 h) | Ccr1.7 = 0 Ccr1.6 = 0 Ccr1.3 = 1 Ccr1.1 = 1 |
| CCR2(1小时) | Ccr2.3 = 1 Ccr2.2 = 1 Ccr2.1 = 0 Ccr2.0 = 0 | CCR2(1小时) | Ccr2.3 = 1 Ccr2.2 = 1 Ccr2.1 = 0 Ccr2.0 = 0 |
| CCR4 (03 h) | Ccr4.7 = ccr4.6 = ccr4.5 = 0 CCR4.1(应用程序依赖) Ccr4.0 = 0 | CCR4 (03 h) | CCR4.7, CCR4.6, CCR4.5(应用程序依赖) CCR4.1(应用程序依赖) Ccr4.0 = 0 |
| CCR5 (04 h) | Ccr5.5 = 0, ccr5.4 = 0 Ccr5.1 = 1, ccr5.0 = 0 (内部Rx侧，100欧姆启用) | CCR5 (04 h) | Ccr5.5 = 0, ccr5.4 = 0 Ccr5.1 = 0, ccr5.0 = 1 (内部RX侧，120欧姆启用) Ccr5.1 = 1, ccr5.0 = 1 (内部Rx侧，75欧姆启用) |
