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* This specification are subject to be changed without notice. 2 4.28.1999 EM91865 13 MEMORY TONE/PULSE DIALER WITH HF, HD, REDIAL AND VOLUME CONTROL FUNCTION Preliminary PIN ASSIGNMENTS PIN DESCRIPTIONS Symbol Function K2 , K3 , K5 ~ K8 Key board scan I/O pins, key scans by ripple way. I/O pin These pins output 16K Hz signal one by one and periodically for key board scan. K1/HDO This pin has two functions Normally this pin will be a Key board scan pins function same as K1~K8. In Hold condition this pin will stay in "High" level to control the Hold circuit and scan HD input key. In Hold condition all key will not allow keying except HD, HF and Hook switch. K4/MuteO This pin has two functions Normally this pin will be a Key board scan pins function same as K1~K8. In MUTE condition this pin will stay in "High" level and output signal with the inverse of key scan to control the MUTE circuit and scan input key. Any key input will release MUTE condition. K6/XMUTE This pin has two functions Normally this pin will be a Key board scan pins function same as K1~K8. The Tone/Pulse dialing Mute signal output pin. This pin will switch to "High" level during Tone/Pulse dialing and hold function. Otherwise, this pin DC level stays "Low". VDD, VSS Positive and negative power supply input pin Xin, Xout Oscillator input and output pins, built in two 5pf capacitor so it's not need external capacitor. A 3.579545 MHz crystal must be crossed between Xin and Xout. HFI Handfree function Input pin accepts rising edge signal to turn "on" or turn "off" handfree function. This pin is hysteresis input structure and built-in pull down resistor (typically 200 K Ω) . HFO Handfree outputs pin that is designed to control telephone line for on-hook dialing or control speakerphone circuit for handfree conversation. When handfree function is executed, this pin will switch to "High". Otherwise, this pin stays "Low" level. HKS Hook Switch detects input pin, which is hysteresis input structure and without internal pull up resistor. DTMF DTMF (Dual Tone Multi-Frequency) output pin, In tone dialing mode, this pin will output DTMF signal that is corresponding to key board 0~9, *, # key. PO Pulse signal output pin that is NMOS open-drain. This pin is for pulse dialing. This output is "Low" during pulse dialing blank duration and Flash operation active, otherwise will be "High impedance". VAO Volume Add output pin , which is open drain structure. Normally this pin will stay in "High Impedance". When Volume add active and dialer in OFF- HOOK mode operting then this pin will output "Low". K7 K6/XMUTE K5 K4/MUTEO XIN XOUT VSS VAO 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 K8 K3 K2 K1/HDO DTMF PO HKS VDD EM91865A EM91865B K7 K6/XMUTE K5 K4/MUTEO XIN XOUT VSS VAO HFI 1 2 3 4 5 6 7 8 9 18 17 16 15 14 13 12 11 10 K8 K3 K2 K1/HDO DTMF PO HKS VDD HFO |
