MH89791 CEPT PCM 30 Transmit Equalizer Advance Information Features ISSUE 4 May 1995 Pin Connections • Used with the MH89790B • Programmable equalization for different line lengths • 6dB loop around circuit TL TL TI Ri RL RL TxT EIT EA L1 EB EC L2 RCHT RCLT TxR EIR SW RCHR RCLR Description The MH89791 is a programmable network for use with a PCM 30 line interface, specifically the MH89790B on The ISDN EXPRESS™ Card. The MH89791 contains transmit equalizer and a 6 dB pad, for external loop around, with 120Ω input and output impedances. It is fabricated in thick film hybrid technology and is 2 inches high by 0.5 inches wide. The MH89791 is designed to interface to 22 gauge/.6 mm twisted pair. Figure 1 shows how the MH89791 is connected to the transmit side of a PCM 30 interface. The seven switches control the distance settings of the equalizer. Ti, Ri, TL, and RL are the inputs and outputs of the 6 dB pad. The 4 pole double throw relay connected to the transformer inputs and outputs shows how the transmit signal is switched between the equalizer for normal operation, 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Ordering Information -40°C to 85°C MH89791 20 Pin SIP Hybrid and the 6dB pad for loop around. Figure 2 shows the circuit description of the MH89791 while Figure 3 shows the switch settings for the Tx equalizer. MH89790B MH89791 OUTA +12V L1 • • • EIT EIR TxT TxR 1: :0.5 S1 C2 1: S2 • OUTB S3 • • • S4 S5 EA EB EC C2 = .47µF L1 = 33 µH SW RCLT S6 RCHT RCLR S7 RCHR Ti TL Ri RL • RxT .8: :1 .8: • RxR Figure 1 - Connection Diagram 4-219 MH89791 Advance Information 240Ω S5 EQUALIZER • • 3600pF S4 468Ω • • • • • 1600pF 6dB Pad • EiT Tip O 60Ω • Tip Line • 60Ω 60Ω 60Ω • 60Ω 60Ω • 120Ω • • 120Ω • 6.8µH 60Ω • 152.4Ω 134.4Ω 60Ω Ring O TxT Ring Line • 60Ω 15µH S1 • • S2 S3 60Ω 60Ω 60Ω • EiR • • • • 1600pF S6 S7 • • 468Ω 3600pF TxR 240Ω Figure 2 - MH89791 Circuit Description -=SWITCH OPENED X=SWITCH CLOSED S1 X - - X - - X - - X - - S2 - X - - X - - X - - X - S3 - - X - - X - - X - - X S4 - - - X X X - - - X X X S5 - - - - - - X X X X X X S6 - - - X X X - - - X X X S7 - - - - - - X X X X X X INCREASING EQUALIZATION NO EQUALIZATION MAX. EQUALIZATION Figure 3 - Switch Settings for Different Levels of Equalization 4-220 MH89791 Advance Information 0.03 Max. (0.8 Max.) 2.00 + 0.02 (50.8 + 0.5) AAAAAAAAAAAA A A AA A AA A AA A AA A AA A AA A AA A AA A AA A AA AAA A AAAA A AAAA AA A AA AA A A AAAA AA A Pin 1AAAA 1 5 10 15 20 0.40 + 0.02 (10.2 + 0.5) Side View Front View 0.010 + 0.002 (0.25 + 0.05) 0.2 Max. (5.1 Max.) 1 5 0.05 ± 0.01 (1.3 ± 0.3) 0.18 + 0.02 (4.6 + 0.5) * Notes: 1) Not to scale. 2) Dimensions in inches 3) (Dimensions in millimeters) 4) Dimension to center of pin 0.05 + 0.02 (1.3 + 0.5) 0.020 + 0.005 (0.51 + 0.13) 0.10 + 0.01 (2.5 + 0.2) Figure 4 - Mechanical Data 4-221 MH89791 NOTES: 4-222 Advance Information