1997 May 14

14

Philips Components

Preliminary specification

Desktop video & FM radio module

system CCIR I

FM1246

Charge pump settings:

CP = 1, for fast tuning

CP = 0, for moderate speed tuning with slightly better residual oscillator FM.

It is recommended to set CP = 1 at all times in the TV mode. In the FM radio mode, set CP = 1 only during the search

tuning. Once the wanted channel is obtained, set CP = 0 to get the best signal-to-noise ratio.

Test mode settings:

T2 = T1 = 0; T0 = 1, for normal operation.

PLL disabling:

OS = 0, for normal operation

Ratio select bits

Notes

1. If the TV function is not required, the tuner can be switched to power-down mode. In this mode the tuner reduces the

current consumption by up to 100 mA.

2. By this setting the FM radio AFC status can be read from the A/D bits in the status byte.

3. By this setting the RF input level can be read from the A/D bits in the status byte.

RSA

RSB

STEP SIZE

X

0

50 kHz (for FM band)

0

1

31.25 kHz (for slow picture search)

1

1

62.5 kHz (for normal picture search)

FUNCTION

BIT

P7

P6

P5

P4

P3

P2

P1

P0

TV/FM bandswitching

FM band

1010

1

Low band

1010

0

Mid band

1001

0

High band

0011

0

TV mode

Power down mode; see note 1

0001

System I negative mode

0000

FM radio mode

AFC; see note 2

0101

0100

Mono

0110

Mute

1100