TDA7326 Datasheet, PDF (11/16 Pages) STMicroelectronics – AM-FM RADIO FREQUENCY SYNTHESIZER

AM SWALLOW MODE
f_REF = 1KHz
F_VCO = (64 ⋅ PC + SC + 64) ⋅ f_REF
FVCO = (DIV_VAL+ 64) ⋅ fREF
swallow 6bit
TDA7326
fREF = 2.5KHz
FVCO = (32 ⋅ PC + SC + 32) ⋅ fREF
F_VCO = (DIV_VAL+ 32) ⋅ f_REF
swallow 5bit (bit SC5 = 0)
AM DIRECT MODE
F_VCO = (DIV_VAL+ 1) ⋅ f_REF
5.2: Examples
a) CONDITIONS:
FM MODE (fRF = 98.1MHz, fREF = 25KHz; IF = 10.7MHz
it follows: that FVCO = 98.1 + 10.7 = 108.8MHz
DIV_VAL
=
F_VCO
f_ref
- 32 =4352 - 32 = 4320 = 10 E 0 Hex
=^{10000 111000000}
PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0 SC5 SC4 SC3 SC2 SC1 SC0
SC = 0 (*)
binary ⇒
PC = 135
b) CONDITIONS:
FM MODE (f_RF = 98.8MHz, f_REF = 25KHz; IF = 10.7MHz
it follows: FVCO = 98.8 + 10.7 = 109.5MHz
DIV_VAL = 4380 - 32 = 4348 = 10 FC Hex
10000111011100
=
PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0 SC5 SC4 SC3 SC2 SC1 SC0
SC = 28 (*)
binary ⇒
PC = 135
NOTE: (*) The bit SC5 is FORCED = 0, and higher weigth bits are left shift ed one position.
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