1997 Apr 08

13

Philips Semiconductors

Preliminary specification

Pre-amplifier for Hard Disk Drive (HDD)

with MR-read/inductive write heads

TDA5155

Notes

1. Unused bits in the registers (indicated by X) are don’t care. Default data, initialized at Power-up, is zero in all

is the LSB of the test mode register and d2 is the d2 data bit of the compensation capacitor register.

0X

X

X

0011

MR current DAC register:

mA

0X

X

X

0100

write current DAC register:

mA

0X

X

X

0101

servo write register:

(d0,d1) = (0,0): one head

(d0,d1) = (1,1): all heads

(d0,d1) = (1,0): odd numbered heads (H1, H3, H5, H7 and H9)

(d0,d1) = (0,1): even numbered heads (H0, H2, H4, H6 and H8)

0X

X

X

0110

test mode register:

(d2,d1,d0) = (0,0,0) = not in test mode

(d2,d1,d0) = (0,1,1) = temperature monitor

(d2,d1,d0) = (1,X,d0) = thermal asperity detection, see note 2

0X

X

X

0111

compensation capacitor register:

equivalent differential capacitance = (4.d2 + 2.d1 + 1.d0)

× 2pF

0X

X

X

1000

high frequency gain attenuator register

nominal pole frequency =

0X

X

X

1001

high frequency gain boost register

nominal zero frequency =

0X

X

X

1010

settle time register

settle time:

1X

X

X

1111

device ID register

ID = 8.d3 + 4.d2 + 2.d1 + 1.d0; d3 to d0 are preset to (0,0,1,1)

1

XXXa3

a2

a1

a0

when a7 = 1, data from the register with address a3 to a0 is read out on

SDATA

FUNCTION

A7 A6 A5 A4 A3 A2 A1 A0

I

MR

0.5

10k

Ω

R

ext

--------------- 10

16.d4

8.d3

4.d2

2.d1

d0

+

++++

()

×

=

I

WR

10k

Ω

R

ext

--------------- 20

16.d4

8.d3

4.d2

2.d1

d0

+

++++

()

=

800 MHz

8.d3

4.d2

2.d1

1.d0

+++

---------------------------------------------------------------------

800 MHz

8.d3

4.d2

2.d1

1.d0

+++

---------------------------------------------------------------------

t

st

2

µs

1

4.d2

2.d1

1.d0

1

+++

()

-------------------------------------------------------------------

µs

+

=