IN9270 Datasheet | Integral

DESCRIPTION Early steering output. Presents a logic high immediately when the digital algorithm detects a recognizable tone-pair (signal condition). Any momentary loss of signal condition will cause ESt to return to a logic low. Gain Select. Gives access to output of front-end differential amplifier for connection of feedback resistor. Internal Connection. Must be tied to GND. Non-Inverting Input Inverting Input Clock Input Clock Output Connections to the front-end differential amplifier. 3.579545 MHz crystal connected between these pins pletes internal oscillator. GS IC IN+ INC1 C2 Q1-Q4 St D 3 5,6 1 2 7 8 11-14 15 3-state data outputs. When enabled by OE, provide the code corresponding to the last valid tone-pair received. Delayed steering output. Presents a logic high when a received tone-pair has been registered and the output latch updated; returns to logic low when the voltage on St/GT falls below VTSt. Steering input/guard time output (bi-directional). A voltage greater than VTSt, detected at St causes the device to register the detected tone-pair and update the output latch. A voltage less than VTSt frees the device to accept a new tone-pair. The GT output acts to reset the external steering time-constant; its state is a function of ESt and the voltage on St. 3-state output enable (input). Logic high enables the outputs Q1-Q4. Internal pullup. Positive power supply, +5 V. Reference voltage output, nominally VCC /2. May be used to bias the inputs at mid-rail. Negative power supply, normally connected to 0 V. St/GT OE VCC VREF GND 10 18 4 9 FUNCTIONAL DESCRIPTION The IN9270 monolithic DTMF receivers offer small size, low power consumption and high performance. The architecture consists of a bandsplit filter section, which separates the high and low tones of a receiver pair, followed by a digital counting section which verifies the frequency and duration of the received tones before passing the corresponding code to the output bus. of two filters - a...