ST7540TR STMicroelectronics, ST7540TR Datasheet - Page 27

• Manufacturer Part Number: ST7540TR
• Description: IC TXRX FSK POWER LINE 28-TSSOP
• Manufacturer: STMicroelectronics
• Type: Transceiverr

Specifications of ST7540TR

• Number Of Drivers/receivers: 1/1
• Voltage - Supply: 5 V ~ 9 V
• Mounting Type: Surface Mount
• Package / Case: 28-TSSOP Exposed Pad, 28-eTSSOP, 28-HTSSOP
• For Use With: 497-5485 - BOARD EVAL ST7540 PWR LINE TXRX
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Protocol: -
• Lead Free Status / Rohs Status: Compliant
• Other names: 497-5528-2

ST7540
In the analog domain, the signal is filtered in order to reduce the output signal spectrum and
to reduce the harmonic distortion. The transition between a symbol and the following is done
at the end of the on-going half FSK sinewave cycle.
Figure 16. Transmitting path block diagram
●
Automatic Level Control (ALC)
The Automatic Level Control Block (ALC) is a variable gain amplifier (with 32 non linear
discrete steps) controlled by two analog feed backs acting at the same time. The ALC
gain range is 0dB to 30 dB and the gain change is clocked at 5KHz. Each step
increases or reduces the voltage of 1dB (Typ).
Two are the control loops acting to define the ALC gain:
–
–
The Voltage control loop acts to keep the Peak-to-Peak Voltage constant on Vsense.
The gain adjustment is related to the result of a peak detection between the Voltage
waveform on Vsense and two internal Voltage references. It is possible to protect the
Voltage Control Loop against noise by freezing the output level (see
Output voltage level
–
–
–
A Voltage Control loop
A Current Control Loop
If Vsense < Vsense
If Vsense
If Vsense > Vsense
TH
- Vsense
freeze).
TH
TH
HYST
- Vsense
+ Vsense
< Vsense < Vsense
HYST
HYST
The next gain level is decreased by 1 step
The next gain level is increased by 1 step
TH
+ Vsense
Functional description
HYST
Section 7.5:
No Gain Change
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