ST7538P STMicroelectronics, ST7538P Datasheet - Page 20

• Manufacturer Part Number: ST7538P
• Description: Telecom Line Management ICs 1/2 Duplex FSK Modem
• Manufacturer: STMicroelectronics
• Type: Single Chipr

Specifications of ST7538P

• Product: Modem Chip
• Supply Voltage (max): 5.25 V, 12.5 V
• Supply Voltage (min): 4.75 V, 7.5 V
• Supply Current: 5 mA, 370 mA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Package / Case: TQFP-44
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ST7538
3.8 Crystal Oscillator
ST7538 integrates a sub-threshold driver circuit to realize a 16MHz crystal oscillator.
This circuit is able to drive a maximum load capacitance of 16pF with typical quartz ESR of 40Ω.
If the internal driver circuit is used, only one external crystal quartz and two external load capacitors (C
e C
Figure 19. Typical crystal configuration if ST7538 internal crystal driver circuit is used
If an external oscillator is used, XIN must be connected to DVss, while XOUT must satisfy the specifica-
tions given in table 5 (see also fig.20).
Figure 20. XOUT waveforms if an external oscillator is used (see table 8 for parameter values)
3.9 Control Register
The ST7538 is a multi-channel and multifunction transceiver. An internal 24 Bits Control Register allows
to manage all the programmable parameters (table 11).
The programmable functions are:
■
■
■
■
■
■
20/30
Channel Frequency
Baud Rate
Deviation
Watchdog
Transmission Timeout
Frequency Detection Time
2
) are needed to realize the oscillator function (fig.19).
XIN = DV
XIN = DV
XOUT
XOUT
SWING
SWING
SS
SS
C
C
XIN
XIN
1
1
ST7538
ST7538
Quartz
Quartz
XOUT
XOUT
C
C
2
2
XOUT
XOUT
OFFSET
OFFSET
1