Table 1. Pin Conﬁgurations—DM207 (Modem Side)
1, 24 C1A, C1B
Capacitor—A 15 nF capacitor (C1) is tied between pin #1 and pin #24. This controls the RC time constant
for the receive optical active bias control.
O Internal 1.25 V precision bandgap reference. Active when Off-hook or in On-hook Monitor mode only. Do
not load this output with more than 1.0 µA.
Capacitor—Typically this 68 nF capacitor (C2) is tied between pin #3 and ground. C2 sets the integrator
response for the lowpass filter of the optical active bias circuit.
O RX Cathode—The receiver photo diode return is connected to pin #7 of the IL388DAA (U3).
I RX Anode—The receive photo diode input and is connected to pin #8 of the IL388DAA (U3). This input
is sensitive to noise relative to VSS and should be routed to minimize pickup from other signal sources.
6 ONHKML I On-hook Monitor Low—Logic Low activates the On-hook Monitor function, which includes an internal
I On-hook Monitor—Logic High activates the On-hook Monitor function, which includes an internal pull
Diagnostic pin. Do not connect.
I Servo Anode—The transmit servo photo diode input is connected to pin #3 of the IL388DAA (U4). This input
is sensitive to noise level relative to VDD and should be routed to minimize pickup from other signal sources.
O Servo Cathode—The transmit servo photo diode current return and is connected to pin #4 of the IL388DAA
(U4). This pin is clamped at 0.8 V.
I TX Amplifier Input—The current (summing mode) input for transmit audio. This input is at ACREF voltage
±5.0 mV. A 120 k resistor between this point and transmit audio source gives unity voltage gain into the
P Power supply voltage. 3.0 to 7.0 V.
O LED Cathode—The transmit linear optocoupler LED cathode is connected to pin #1 of the IL388DAA (U4).
The printed circuit board layout should minimize capacitive coupling between this trace and the SRVAN and
P Power supply return (Ground).
O Auxiliary amplifier output— will drive a 300 Ω load.
I Inverting input for an auxiliary amplifier. The non-inverting input is internally tied to ACREF.
O A 25.5 k, 1% resistor to ground sets the transmit DC bias point of U4.
I/O Audio DC reference for transmit and receive signals. 1.25 V reference @ 1.0 µA maximum output. It can be
overdriven by connecting an external voltage source. This output is turned off during idle mode (On-hook,
and no snoop).
O Audio Output –6.0 dB relative to the telephone line. It has 300 Ω drive capability. This output goes to a high
impedance state in idle mode. DC voltage is ACREF.
I OFF-HOOK—Positive assertion Off-hook control input. Includes an internal pull-down resistor.
I OFF-HOOK LOW—Negative assertion Off-hook control input. Includes an internal pull-up resistor
O RING Detect—In IDLE modes it outputs a 4 ms positive pulse for each full cycle or half cycle depending on
the value of pin #7 on the DL207. In snoop or Off-hook modes, the output is the same as LSTAT.
O Line Status—In idle mode, this pin outputs a series of pulses whose frequency is directly related to line volt-
age (V/f function). In snoop or Off-hook modes, the output will give a single pulse if the line current is sud-
denly decreased indicating a parallel phone going Off-hook.
See above – pin #1.
2000 Inﬁneon Technologies Corp. • Optoelectronics Division • San Jose, CA
www.inﬁneon.com/opto • 1-888-Inﬁneon (1-888-463-4636)
OSRAM Opto Semiconductors GmbH & Co. OHG • Regensburg, Germany
www.osram-os.com • +49-941-202-7178
July 14, 2000-14