U3550BM Datasheet, PDF (12/25 Pages) TEMIC Semiconductors – Low-Power FM Transmitter / Synthesizer System 26 to 50 MHz

U3550BM
Fine Adjustment of the Oscillator Frequency
To set the oscillator’s frequency exactly to 11.5 MHz, the frequency is adjustable in 8 steps. By adding 3 different
internal capacities, the frequency can be reduced. The values of these capacitors are designed to be 0.7 pF (FAO0),
1.4 pF (FAO1) and 2.8 pF (FAO2).
Parameters
Oscillator frequency without
reduction
Changing the oscillator’s
frequency with FOSC reduction
Test Conditions / Pins
FAOS (0:2) = 0
FAO2 FAO1 FAO0
00
1
01
0
10
0
11
1
Min.
Typ.
Max.
Unit
11.15
MHz
100
Hz
200
Hz
400
Hz
700
Hz
Test Circuit
f = 1 kHz
V_rms = 500 mV
V_offset = 1.5 V
V_CC
V_MCKA
DC +
DC +
sin
C_{9 1 µF}
+
0.1 µF
C₈ ^R5
V_Batt
5.6 k Ω
DC +
28
27
26
25
24
23
22
21
V_RFOVB
DC +
W ^R4
200
20
19
18
17
C₆
56 nF
C₇
W ^R3
24 k
4.7 nF
16
15
U3550BM
1
2
3
4
D
C
Inputs serial bus
11.15
MHz
13281
5
6
7
8
9
10
11
12
13
14
V_OSC
V_DD +
+
V_Batt
DC DC V_DELVB
C₁
4.7 pF
C₂
10 nF
C₃
1 nF
sin
V_MIX
V_B +
110 nH
W ^R1
330
L₁
DC
C₄ ^C5
10 nF
+
*⁾
W ^{f = fRF}
R_out = 50
D₁
V_rms = 2.24 mV
12 pF _*)
D₂
R₃
56 kW
Figure 8. Test circuit
*^{) BPY51 or}
BZT55C51
12 (25)
Preliminary Information
Rev. A2, 10-Sep-98