Datasheet

DS_1903_032 73M1903 Data Sheet

Rev. 2.1 29

8.4 Analog Specifications

8.4.1 DC Specifications

VREF should be connected to an external bypass capacitor with a minimum value of 0.1 μF. This pin is

not intended for any other external use.

Table 15: Reference Voltage Specifications

Parameter Test Condition Min Nom Max Units

VREF VDD= 3.0 V - 3.6 V.

1.36

VREF Noise 300Hz-3.3 kHz -86 -80 dBm

600

VREF PSRR 300Hz-30 kHz 40* dB

8.4.2 AC Specifications

Table 16 shows the maximum transmit levels that the output drivers can deliver before distortion through

the DAA starts to become significant. The loss though the DAA transmit path is assumed to be 7 dB.

The signals presented at TXAP and TXAN are symmetrical. The transmit levels can be increased by

setting either TXBST0 (+1.5 dB) or/and TXBST1 (+0.83 dB) for the combined total gain of 2.33 dB.

These can be used where higher-level DTMF tones are required.

Table 16: Maximum Transmit Levels

Transmit Type

Maximum Different

Line Level (dBm0)

Maximum Single-

Ended Level at

TXA Pins (dBm)

Peak to

rms Ratio

Single-Ended

rms Voltage at

TXA Pins (V)

Single-Ended

Peak Voltage

at TXA Pins (v)

VPA=2.7 V to 3.6 V. All rms and peak voltages are relative to VREF.

V.90 -12.0 -11.0

0.2175 0.87

QAM -7.3 -6.3 2.31 0.377 0.87

DPSK -5.1 -4.1 1.81 0.481 0.87

FSK -3.0 -2.0 1.41 0.616 0.87

DTMF (high tone) -7.8 -6.8 1.41 0.354 0.500

DTMF (low tone) -9.8 -8.8 1.41 0.283 0.400