75T2090

Features:

` DTMF Generator and Receiver on one-chip
` Call progress detection (2090/2091 only)
` Early detect output (2091 only)
` DTMF Receiver exhibits excellent speech immunity
` Analog input range from -32 to -2 dBm (ref 600)
` Three-state outputs (4-bit hexadecimal) from DTMF Receiver
` AC coupled, internally biased analog input
` Latched DTMF Generator inputs
` DTMF output typ. -8 dBm (Low Band) and -5.5 dBm (High Band)
` Easy interface for microprocessor dialing
` Uses inexpensive 3.579545 MHz crystal for reference
` Low-power 5 volt CMOS


Pinout

Specifications

PARAMETER	RATING
DC Supply Voltage (Vp - Vn)	+7V
Voltage at any Pin (Vn = 0)	-0.3 to Vp + 0.3V
DIN Voltage	Vp + 0.5 to Vp - 10V
Current through any Protection Device	=20mA
Operating Temperature Range	-40 to + 85°C
Storage Temperature	-65 to 150°C

Description

TDK Semiconductor's 75T2090 are complete Dual-Tone Multifrequency (DTMF) Transceivers that can both generate and detect all 16 DTMF tone-pairs. These ICs integrate the performance-proven 75T202 DTMF receiver with a DTMF generator circuit.

The DTMF receiver electrical characteristics of the 75T2090 are identical to the standard 75T202 device characteristics. The DTMF generator provides performance similar to the Mostek MK5380, but with an improved (tighter) output amplitude range specification and with the addition of independent latch and reset controls.

An additional feature of the 75T2090 is "imprecise" call progress detector. The detector detects the presence of signals in the 305-640 Hz band.

The 75T2090 also incorporates an early detect function which is useful in multi-channel radio scanning applications. The only external components necessary for the 75T2090 are a 3.58 MHz "colorburst" crystal with a parallel 1 MW resistor. This provides the time base for digital functions and switched-capacitor filters in the device.No external filtering is required.