si4021 Silicon Laboratories, si4021 Datasheet - Page 16

• Manufacturer Part Number: si4021
• Description: Si4021 Universal Ism Band Fsk Transmitter
• Manufacturer: Silicon Laboratories

6. Low Battery Detector Command
Bit 7 <dwc> Disables the Wake-up timer periodical (every 30 second) calibration if this bit is set.
Bit 5 <ebs> Enables the TX bit synchronization circuit. The data rate must be set by the Data Rate Command.
The 5-bit value T of <t4 : t0> determines the threshold voltage V
7. Sleep Command
The effect of this command depends on the Power Management Command. It immediately disables the power amplifier (if a0=1 and ea=0)
and the synthesizer (if a1=1 and es=0). Stops the crystal oscillator after S periods of the microcontroller clock (if a1=1 and ex=0) to enable
the microcontroller to execute all necessary commands before entering sleep mode itself. The 8-bit value S is determined by bits <s7 : s0>.
bit
bit
15
15
1
1
V
lb
14
14
1
1
= 2.25 V + T * 0.1 V
13
13
0
0
12
12
0
0
11
11
0
0
10
10
0
1
9
1
9
0
8
0
8
0
dwc
s7
7
7
lb
of the detector:
s6
6
0
6
ebs
s5
5
5
s4
t4
4
4
s3
t3
3
3
s2
t2
2
2
s1
t1
1
1
s0
t0
0
0
C200h
C410h
POR
POR
IA4221
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