L3845B

L3845 ® TRUNK INTERFACE ON CHIP POLARITY GUARD MEETS DC LINE CHARACTERISTICS OF EITHER CCITT AND EIA RS 464 SPECS PULSE FUNCTION HIGH AC IMPEDANCE OFF HOOK-STATUS DETECTION OUTPUT LOW EXTERNAL COMPONENT COUNT Minidip DESCRIPTION The circuit provides DC loop termination for analog trunk lines. The V-I characteristics is equivalent to a fixed voltage drop (zener like characteristic) in series with an external resistance that determines the slope of the DC characteristic. An external low voltage electrolytic capacitor causes the circuit to exhibit a very high impedance to all AC signal above a minimum frequency that is determined by the capacitor itself and by a 20 K nominal resistor integrated on the chip. The Off-Hook status is detected all the time a typic of 8 mA is flowing into the circuit. In this condition a constant current generator is activated to ) s ( ct BLOCK DIAGRAM SO8 SO20W (12+4+4) ORDERING NUMBERS: L3845B c u d L3845D e t le ) s t( L3845-20 o r P supply an external device (typically an optocoupler) without affecting the AC characteristic of the circuit. When Pulse Dialing is required the PULSE input (pin 3) connected to V- causes the device to reduce the fixed DC voltage drop and to exhibit a pure resistive impedance equal to the external resistor. o s b O - u d o r P e t e l o bs O IN1 8 1 3 DC LINE TERMINATION POLARITY GUARD IN2 OF HOOK DETECTION CIRCUIT 7 5 6 2 ACT DCT V- R2 R3 C1 4 V+ PULSE HD0 S2 R1 S1 D96TL263 September 2003 1/8 This is advanced information on a new product now in development or undergoing evaluation. Details are subject to change without notice. L3845 ABSOLUTE MAXIMUM RATINGS Symbol VL IL Ptot Top Tsrg, Tj Value Unit Max Line Voltage (pulse duration 10 ms max) Parameter 20 V Max Line Current Total Power Dissipation at Tamb = 70 °C 150 800 mA mW – 40 to + 70 – 55 to + 150 °C °C Operating Temperature Storage and Junction Temperature PIN CONNECTION (Top view) SO20 MINIDIP and SO8 PULSE 1 20 V- HD0 2 19 IN1 NC 3 18 NC SUBS 4 17 SUBS SUBS 5 16 IN1 1 SUBS V- 2 3 SUBS 6 15 SUBS PULSE SUBS 7 14 SUBS HD0 NC 8 13 NC ACT 9 12 V+ DCT 10 11 IN2 SO20 ) s ( ct c u d e t le o s b O - 4 ) s t( 8 V+ 7 IN2 6 DCT 5 ACT o r P DIP8 SUBS = the pin is electrically and thermally in good contact with the chip sustrate. Connect to PCB copper tracks, for heat dissipation the tracks shall preferably be electrically connected to pin 20 (internally bonded to the chip substrate) or left floating. A higher track density and/or area assures a Rth j-amb towards the lower limit. r P e THERMAL DATA Symbol t e l o Rth j-amb 2/8 Parameter Thermal Resistance Junction-ambient (*) (*) Mounted on FR4 Boards s b O u d o Max. Minidip SO8 SO20 Unit 80 140 to 180 50 to 70 °C/W L3845 DC ELECTRICAL CHARACTERISTICS (IL = 10 mA to 100 mA, R1 = 56 Ω, S1 = Open, Tamb = + 25 °C, unless otherwise specified) Symbol VL VLP Max. Unit Line Voltage (normal mode) Parameter PULSE = Open IL = 10 mA IL = 20 mA IL = 100 mA Test Condition Min. Typ. 5 6 12 V V V Line Voltage (pulse mode) PULSE = V– IL = 20 mA IL = 35 mA IL = 80 mA 4 5.5 9.5 V V V Ihn ON/OFF-Hook Line Current Detection Threshold 6.5 9.5 mA Ihf OFF/ON-Hook Line Current Detection Threshold 5 9.2 mA IOUT OFF-Hook Output Drive Current at Pin HDO VPM Pulse Input Low Voltage IPM Pull-up Input Current at Pin PULSE (pulse mode) INM Imput Current at Pin Pulse (normal mode) IL = 10 mA IL ≥ 20 mA 1.5 1.8 IL = 100 mA Pulse = V– mA mA P e let V 20 µA 3 µA c u d ro ) s t( 0.8 AC ELECTRICAL CHARACTERISTICS (I L = 10mA to 100mA, R1 = 56Ω, R2 = 470KΩ, R3 = 130 KΩ, Tamb = + 25 °C, unless otherwise specified) Symbol Parameter S1 = Open, S2 = Open C1 = 2.2mF f = 1KHz ) s ( ct Sending/Receiving Distortion u d o Sending/Receiving Distortion r P e Sending/Receiving Distortion t e l o o s b O Test Condition AC Line Impedance ZL Min. Typ. 20 S1 = Open, S2 = Open f = 1KHz VAC-L = 775mVrms IL = 15 to 100mA S1 = Closed; S2 = Open VAC-L = 1.3Vrms S1 = Open; S2 = Closed VAC-L = 1.9Vrms Max. Unit KΩ 2 % 2 % 2(*) % (*) Not tested, guaranteed only by design. APPLICATION INFORMATION With the use of this circuit it is possible to terminate an analog trunk so that all the DC current component is flowing in the TRUNK TERMINATION CIRCUIT while the AC component is decoupled with a low voltage capacitor and can be used with a small and low cost audio coupler transformer to provide the AC balancing termination and two to four wire conversion. Therefore it is usefull both for MODEM and PABX systems. s b O Figure 1 gives the typical application circuit ; it is worth to note that the TRUNK TERMINATION CIRCUIT, together with the LS5018 transient suppressor provides a compact and low cost module fully protected against lightning or overvoltages frequently present on telephone lines. The PULSE input when connected to V- allows the device to reduce the Line Voltage and to show a resistive impedance equal to R1 to the line. When PULSE input is left open, this function is disable. 3/8 L3845 Figure 1: Typical Application. c u d e t le ) s ( ct u d o r P e t e l o s b O 4/8 o s b O - o r P ) s t( L3845 mm inch OUTLINE AND MECHANICAL DATA DIM. MIN. A TYP. MAX. MIN. 3.32 TYP. MAX. 0.131 a1 0.51 0.020 B 1.15 1.65 0.045 0.065 b 0.356 0.55 0.014 0.022 b1 0.204 0.304 0.008 0.012 D E 10.92 7.95 9.75 0.430 0.313 0.384 e 2.54 0.100 e3 7.62 0.300 e4 7.62 0.300 F 6.6 0.260 I 5.08 0.200 L 3.18 Z 3.81 0.125 1.52 0.150 c u d ) s ( ct o r P Minidip e t le 0.060 ) s t( o s b O - u d o r P e t e l o s b O 5/8 L3845 mm DIM. MIN. TYP. A inch MAX. MIN. TYP. 1.75 a1 0.1 0.25 a3 0.65 b MAX. 0.069 0.004 0.010 0.85 0.026 0.033 0.35 0.48 0.014 0.019 b1 0.19 0.25 0.007 0.010 C 0.25 0.5 0.010 0.020 a2 1.65 c1 OUTLINE AND MECHANICAL DATA 0.065 45° (typ.) D (1) 4.8 5.0 0.189 0.197 E 5.8 6.2 0.228 0.244 e 1.27 0.050 e3 3.81 0.150 F (1) 3.8 4.0 0.15 0.157 L 0.4 1.27 0.016 0.050 M 0.6 0.024 c u SO8 d o r P e let 8 ° (max.) S (1) D and F do not include mold flash or protrusions. Mold flash or potrusions shall not exceed 0.15mm (.006inch). ) s ( ct u d o r P e t e l o s b O 6/8 o s b O - ) s t( L3845 mm inch OUTLINE AND MECHANICAL DATA DIM. MIN. TYP. MAX. MIN. TYP. MAX. A 2.35 2.65 0.093 0.104 A1 0.1 0.3 0.004 0.012 B 0.33 0.51 0.013 0.020 C 0.23 0.32 0.009 0.013 D 12.6 13 0.496 0.512 E 7.4 7.6 0.291 0.299 e 1.27 0.050 H 10 10.65 0.394 0.419 h 0.25 0.75 0.010 0.030 L 0.4 1.27 0.016 0.050 K c u d e t le 0˚ (min.)8˚ (max.) o s b O - L ) s ( ct u d o B r P e s b O t e l o ) s t( o r P SO20 h x 45˚ A e A1 K C H D 20 11 E 1 0 1 SO20MEC 7/8 L3845 c u d e t le ) s ( ct ) s t( o r P o s b O - u d o r P e t e l o s b O Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics. 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