CMX625P4 CMLMICRO [CML Microcircuits], CMX625P4 Datasheet - Page 17

• Manufacturer Part Number: CMX625P4
• Description: ISDN TA POTS Interface
• Manufacturer: CMLMICRO [CML Microcircuits]

ISDN TA POTS Interface
1.5.10 SPM Generator
This block operates independently and has its own output pin. It can transmit 12kHz or 16kHz and is
controlled by bit 4 of the SETUP Register. Bit 7 of the MODE Register is used to enable or disable this
block. The signal has a rise and fall time each of about 4ms. The SPM signal rises from the bias level to
0dBm in 16 steps of 2dB magnitude, and falls from 0dBm to bias level in 16 steps of 2dB magnitude.
1.5.11 Transmit Signal Control
This block adjusts the amplitude of the FSK transmit signal output level, the level skew between DTMF
tones and the signal routing to the output ports.
Output signal levels are proportional to V
= 5.0V) are:
The level attenuator provides for level adjustment from 0dB to -14dB in -2dB steps. The typical level is
determined by bits 2 to 4 of the MODE Register as shown in the table below:
The RING signal is a square, trapezoidal or sinusoidal wave. The square and trapezoidal wave have an
amplitude of
trapezoidal ringing waveform has a crest factor (CF) of 1.35. Bits 2 and 3 of the SETUP Register select
the waveform type as shown in the table below.
2001 Consumer Microcircuits Limited
V
DD
peak to peak and the sinusoidal wave has an amplitude of
Bit 4
Bit 3
0
0
0
0
1
1
1
1
SETUP Register
0
0
1
MODE Register
Single Tone
Dual Tone (per tone)
DTMF High Frequency Tone
DTMF Low Frequency Tone
FSK Signal
Bit 3
0
0
1
1
0
0
1
1
DD
Bit 2
0
1
0
. The nominal output signal levels (at 0dB attenuation and V
Bit 2
0
1
0
1
0
1
0
1
17
Signal Level Adjustment
RING Signal Select
Trapezoidal wave
Sinusoidal wave
Square wave
(dB)
-10
-12
-14
-2
-4
-6
-8
0
-3dBm
-3dBm
-5dBm
0dBm
0dBm
½ V
DD
peak to peak. The
CMX625
D/625/2
DD