TDA5153 Datasheet, PDF (22/28 Pages) NXP Semiconductors – Pre-amplifier for Hard Disk Drive HDD with MR-read/inductive write heads

Philips Semiconductors
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
Preliminary specification
TDA5153
5. The PSRR (in dB) is defined as input referred ratio:
PSRR
=
20
×
log



G-G----_p^-v



Where G_v is the differential input to differential output
gain, and G_p is the power supply to differential output
gain. The CMRR (in dB) is defined as input referred
ratio:
CMRR
=
20
×
log



G---G--_c^--v-_m^--



where G_v is the differential input to differential output
gain and G_cm is the common mode input to differential
output gain. Flex and board lay-out may affect
significantly these parameters.
6. This refers to the crosstalk from SCLK and SDATA
inputs via the read inputs to RDx − RDy. Two cases
can be distinguished:
a) With SEN LOW, SCLK and SDATA are prohibited
from entering the device and crosstalk is low.
b) Programming via the serial interface is done with
SEN HIGH. Then crosstalk can occur. A careful
design of the board or flex-foil is required in order
not to get crosstalk via this path.
7. A 200 mV peak-to-peak signal is applied to SCLK or
SDATA inputs at 25 MHz, and measurement is
performed at RDx − RDy.
8. The rise and fall times depend on the write
amplifier-write head combination. L_h and R_h represent
the components on the evaluation board. Parasitic
capacitances also limit the performance.
9. The write current rise/fall time asymmetry is defined by
-2----₍-t--t^r--_r-^–--₊--t--^f-t--_f-₎--
10. Write-to-read recovery time includes the write mode to
read mode switching using the R/W pin on the same
head (see Fig.6). The AC signal reaches its full
amplitude few tenth of ns after appearing at the reader
RDx and RDy outputs.
11. In read mode, the head switching, standby to read
active switching and changing MR current include fast
current settling (see Fig.7). Same note regarding the
AC signals at the reader outputs as above.
12. Write settle time includes read mode to write mode
switching using the R/W pin.
13. The typical supply current in read mode depends on
the bias current for the MR element.
14. The typical supply current in write mode also depends
on the write current.
Table 1 Noise figure
R_MR (Ω)
20
25
30
I_MR = 7 mA
2.7
2.8
2.9
F (dB)
I_MR = 10 mA
2.9
3.0
3.1
I_MR = 15 mA
3.1
3.3
3.5
1997 Jul 02
22