November 1991

6

Philips Semiconductors

Product specification

TSA5515T

FUNCTIONAL DESCRIPTION

programming, there is one module address (7 bits) and the

R/W bit for selecting READ or WRITE mode.

WRITE mode:

R/W = 0 (see Table 1)

After the address transmission (first byte), data bytes can

be sent to the device. Four data bytes are needed to fully

program the TSA5515T. The bus transceiver has an

auto-increment facility, which permits the programming of

the TSA5515T within one single transmission

(address + 4 data bytes).

The TSA5515T can also be partly programmed on the

condition that the first data byte following the address is

byte 2 or byte 4. The meaning of the bits in the data bytes

is given in Table 1. The first bit of the first data byte

transmitted indicates whether frequency data (first bit = 0)

or charge pump and port information (first bit = 1) will

controller, additional data bytes can be entered without the

need to re-address the device. This allows a smooth

frequency sweep for fine tuning. At power-on, the ports are

set to the high impedance state.

The 7.8125 kHz reference frequency is obtained by

dividing the output of the 4 MHz crystal oscillator by 512.

Because the input of the UHF/VHF signal is first divided by

8, the step size is 62.5 kHz. A 3.2 MHz crystal can offer a

step size of 50 kHz.

Table 1

Write data format

MA1, MA0 programmable address bits (see Table 3)

Note

1. X = don’t care

MSB

LSB

Address

1

1000

MA1

MA0

0

A

byte 1

Programmable

divider

0

N14

N13

N12

N11

N10

N9

N8

A

byte 2

Programmable

divider

N7

N6

N5

N4

N3

N2

N1

N0

A

byte 3

Charge-pump

and test bits

1

CP

T1

T0

X

X

X

OS

A

byte 4

Output ports control

bits

P7

XXXX

P2

P1

X

A

byte 5

A

acknowledge bit

N14 to N0

programmable divider bits

N = N14

CP

charge-pump current

CP = 0

50

µA

CP = 1

220

µA

P7, P2, P1 = 1

open-collector outputs are active

P7, P2, P1 = 0

outputs are in high impedance state

T1, T0, OS = 0 0 0

normal operation

T0 = 1

3-state charge-pump

OS = 1

operational amplifier output is switched off (varicap drive disable)