PHILIPS TDA5155

INTEGRATED CIRCUITS
DATA SHEET
TDA5155
Pre-amplifier for Hard Disk Drive
(HDD) with MR-read/inductive write
heads
Preliminary specification
File under Integrated Circuits, IC11
1997 Apr 08
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
CONTENTS
1
FEATURES
2
APPLICATIONS
3
GENERAL DESCRIPTION
4
ORDERING INFORMATION
5
QUICK REFERENCE DATA
6
BLOCK DIAGRAM
7
PINNING
8
FUNCTIONAL DESCRIPTION
8.1
8.2
8.3
8.4
8.5
8.6
8.6.1
8.6.2
8.6.3
8.7
8.7.1
8.7.2
8.7.3
8.7.4
8.7.5
8.7.6
8.7.7
8.7.8
8.7.9
8.7.10
8.8
8.9
Read mode
Write mode
Sleep mode
Standby mode
Active mode
Bi-directional serial interface
Addressing
Programming data
Reading data
Operation of the serial interface
Configuration
Power control
Head select
Servo write
Test
Write amplifier programmable capacitors
High frequency gain attenuator register
High frequency gain boost register
Settle pulse
Address registers summary
Head unsafe
HUS survey
9
LIMITING VALUES
10
HANDLING
11
THERMAL RESISTANCE
12
RECOMMENDED OPERATION
CONDITIONS
13
CHARACTERISTICS
14
DEFINITIONS
15
LIFE SUPPORT APPLICATIONS
1997 Apr 08
2
TDA5155
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
1
FEATURES
3
• Designed for 10 dual-stripe MR-read/inductive write
heads
• Single supply voltage (5.0 V ±10%); a separate write
drivers supply pin can be biased from VCC to 8 V +10%
• MR elements connected to ground (GND)
• Equal bias currents in the two MR stripes of each head
• On-chip AC couplings eliminate MR head DC offset
• 3-wire serial interface for programming
• Programmable voltage/current mode write data input
The device incorporates read amplifiers, write amplifiers, a
serial interface, digital-to-analog converters, reference and
control circuits which all operate on a single supply voltage
of 5 V ±10%. The output drivers have a separate supply
voltage pin which can be connected to a higher supply
voltage of up to 8 V +10%. The complementary output
stages of the write amplifier allow writing with near
rail-to-rail peak voltages across the inductive write head.
• Programmable high frequency zero-pole gain boost
• Programmable write driver compensation capacitance
• Programmable MR bias currents and write currents
• 1-bit programmable read gain
• Sleep, standby, active and test modes available
• Measurement of head resistances in test mode
• In test mode, one MR bias current may be forced to a
minimum current
The read amplifier has low input impedance. The DC offset
between the two stripes of the MR head is eliminated using
on-chip AC coupling. Fast settling features are used to
keep the transients short. As an option, the read amplifier
may be left biased during writing so as to reduce the
duration of these transients even further. Series
inductance in the leads between the amplifier and
MR heads influences the bandwidth which can be
compensated by using a programmable high frequency
gain boost (HF zero). HF noise and bandwidth can be
attenuated using a programmable high frequency gain
attenuator (HF pole).
• Short write current rise and fall times with near
rail-to-rail voltage swing
• Head unsafe pin for signalling of abnormal conditions
and behaviour
• Low supply voltage write current inhibit (active or
inactive)
• Support servo writing
• Provide temperature monitor
• Thermal asperity detection with programmable
threshold level
On-chip digital-to-analog converters for MR bias currents
and write currents are programmed via a 3-wire serial
interface. Head selection, mode control, testing and servo
writing can also be programmed using the serial interface.
In sleep mode the CMOS serial interface is operational.
Fig.1 shows the block diagram of the device.
• Requires only one external resistor.
APPLICATIONS
• Hard Disk Drive (HDD).
4
GENERAL DESCRIPTION
The 5.0 V pre-amplifier for HDD applications has been
designed for five terminal, dual-stripe
Magneto-Resistive (MR)-read/inductive write heads.
The disks of the disk drive are connected to ground.
To avoid voltage breakthrough between the heads and the
disk, the MR elements of the heads are also connected to
ground. The symmetry of the dual-stripe head-amplifier
combination automatically distinguishes between the
differential signals such as signals and the common-mode
effects like interference. The latter are rejected by the
amplifier.
• Current bias-current sense architecture
2
TDA5155
ORDERING INFORMATION
PACKAGE
TYPE
NUMBER
NAME
TDA5155X
−
1997 Apr 08
DESCRIPTION
VERSION
−
naked die
3
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
5
TDA5155
QUICK REFERENCE DATA
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
VCC
supply voltage
4.5
5.0
5.5
V
VCC(WD)
supply voltage for write drivers
VCC
8.0
8.8
V
Gv(dif)
differential voltage gain
from head inputs to RDx, RDy;
RMR = 28 Ω; IMR = 10 mA
data bit d4 = 0
−
160
−
data bit d4 = 1
−
226
−
B−3dB
−3 dB frequency bandwidth
upper bandwidth without gain
boost (4 nH lead inductance)
−
220
−
MHz
F
noise figure
RMR = 28 Ω; IMR = 10 mA;
Tamb = 25 °C; f = 20 MHz
−
3.0
3.2
dB
Virn
input referred noise voltage
RMR = 28 Ω; IMR = 10 mA;
Tamb = 25 °C; f = 20 MHz
−
0.9
1.0
nV/√Hz
CMRR
common mode rejection ratio
RMR mismatch <5%
IMR = 10 mA
f < 1 MHz
−
45
−
dB
f < 100 MHz
−
25
−
dB
−
80
−
dB
−
50
−
dB
VCC(WD) = 8.0 V
−
−
1.8
ns
VCC(WD) = 6.5 V
−
−
2.1
ns
PSRR
IMR = 10 mA
power supply rejection ratio
(input referred) RMR mismatch <5%
f < 1 MHz
f < 100 MHz
tr, tf
write current rise/fall time
(10% to 90%)
Lh = 150 nH; Rh = 10 Ω;
IWR = 35 mA; f = 20 MHz
IMR(PR)
programming MR bias current
range
Rext = 10 kΩ
5
−
20.5
mA
IWR(b-p)
programming write current range
(base-to-peak)
Rext = 10 kΩ
20
−
51
mA
fSCLK
serial interface clock rate
−
−
25
MHz
1997 Apr 08
4
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
6
TDA5155
BLOCK DIAGRAM
handbook, full pagewidth
VCC
VCC(WD)
16
1
(5 to 8 V)
TDA5155
WDlx(i)
WDly(i)
WDlx(v)
WDly(v)
HUS
7
4
WRITE DRIVER
INPUT
FF
19, 24,
10
29, 34, 39, 44,
49, 54, 59, 64
5
3
nWy
nWx
HEAD UNSAFE
INDICATOR
LOW SUPPLY
VOLTAGE
INDICATOR
Rext
20, 25, 30, 35,
40, 45, 50, 55,
60, 65
10
6
WRITE
CURRENT
SOURCE
10
17
WRITE DRIVER
AND
READ PREAMP
(10×)
VOLTAGE
REFERENCE
+VCC
TAS
DETECTOR
8
R/W
SCLK
SEN
SDATA
11
SERIAL
INTERFACE
4
9
10
20 kΩ
head select
5
3
10
RMR
CURRENT
SOURCE
5
23, 28, 33, 38,
43, 48, 53, 58,
10
63, 68
4
4
22, 27, 32, 37,
42, 47, 52, 57,
10
62, 67
13
RDx
RDy
14
21, 26, 31, 36,
41, 46, 51, 56,
10
61, 66
2, 12, 15, 18
MGG982
GNDn
Fig.1 Block diagram.
1997 Apr 08
5
nRy
nGND
nRx
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
7
TDA5155
PINNING
SYMBOL PAD
VCC(WD)
GND1
HUS
WDIx(v)
1
2
3
4
WDIy(v)
5
WDIx(i)
6
WDIy(i)
7
R/W
8
SEN
SDATA
SCLK
GND2
RDx
RDy
GND3
VCC
Rext
GND4
0Wx
9
10
11
12
13
14
15
16
17
18
19
0Wy
20
0Rx
21
0GND
0Ry
22
23
1Wx
24
1Wy
25
1Rx
26
1GND
1Ry
27
28
2Wx
29
1997 Apr 08
SYMBOL PAD
DESCRIPTION
supply voltage for the write drivers
ground connection 1
head unsafe output
write data input (differential, voltage
input)
write data input (differential, voltage
input)
write data input (differential, current
input)
write data input (differential, current
input)
read/write (read = active HIGH,
write = active LOW)
serial bus enable
serial bus data
serial bus clock
ground connection 2
read data output (differential x − y)
read data output (differential x − y)
ground connection 3
supply voltage
10 kΩ external resistor
ground connection 4
inductive write head connection for
head H0 (differential x − y)
inductive write head connection for
head H0 (differential x − y)
MR-read head connection for head
H0 (differential x − y)
ground connection for head H0
MR-read head connection for head
H0 (differential x − y)
inductive write head connection for
head H1 (differential x − y)
inductive write head connection for
head H1 (differential x − y)
MR-read head connection for head
H1 (differential x − y)
ground connection for head H1
MR-read head connection for head
H1 (differential x − y)
inductive write head connection for
head H2 (differential x − y)
6
2Wy
30
2Rx
31
2GND
2Ry
32
33
3Wx
34
3Wy
35
3Rx
36
3GND
3Ry
37
38
4Wx
39
4Wy
40
4Rx
41
4GND
4Ry
42
43
5Wx
44
5Wy
45
5Rx
46
5GND
5Ry
47
48
6Wx
49
6Wy
50
6Rx
51
6GND
6Ry
52
53
7Wx
54
DESCRIPTION
inductive write head connection for
head H2 (differential x − y)
MR-read head connection for head
H2 (differential x − y)
ground connection for head H2
MR-read head connection for head
H2 (differential x − y)
inductive write head connection for
head H3 (differential x − y)
inductive write head connection for
head H3 (differential x − y)
MR-read head connection for head
H3 (differential x − y)
ground connection for head H3
MR-read head connection for head
H3 (differential x − y)
inductive write head connection for
head H4 (differential x − y)
inductive write head connection for
head H4 (differential x − y)
MR-read head connection for head
H4 (differential x − y)
ground connection for head H4
MR-read head connection for head
H4 (differential x − y)
inductive write head connection for
head H5 (differential x − y)
inductive write head connection for
head H5 (differential x − y)
MR-read head connection for head
H5 (differential x − y)
ground connection for head H5
MR-read head connection for head
H5 (differential x − y)
inductive write head connection for
head H6 (differential x − y)
inductive write head connection for
head H6 (differential x − y)
MR-read head connection for head
H6 (differential x − y)
ground connection for head H6
MR-read head connection for head
H6 (differential x − y)
inductive write head connection for
head H7 (differential x − y)
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
SYMBOL PAD
8GND
8Rx
8Wy
8Wx
7Ry
7GND
7Rx
7Wy
7Wx
67
68
8Ry
handbook, full pagewidth
9GND
9Ry
68
67
66
65
64 63
62
61
60
59
58
57
56
55
54
53
6Ry
52
6GND
2
51
6Rx
3
50
6Wy
4
49
6Wx
5
48
5Ry
6
47
5GND
7
46
5Rx
R/W
8
45
5Wy
SEN
9
44
5Wx
VCC(WD)
1
GND1
HUS
WDIx(v)
WDIy(v)
WDIx(i)
WDIy(i)
TDA5155
SDATA
10
43
4Ry
4Wy
39
4Wx
GND3
15
38
3Ry
VCC
16
37
3GND
Rext
17
36
3Rx
GND4
18
35
3Wy
3Wx
0
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33 34
2Ry
40
14
2GND
13
RDy
2Rx
RDx
2Wy
4Rx
2Wx
4GND
41
1Ry
42
12
1GND
11
1Rx
SCLK
GND2
1Wy
61
66
1Wx
8Rx
9Rx
9Wx
60
65
0Ry
8Wy
9Wy
9Wy
59
64
0GND
8Wx
9Wx
9Rx
57
58
Fig.2 Pad arrangement.
1997 Apr 08
ground connection for head H8
MR-read head connection for head
H8 (differential x − y)
inductive write head connection for
head H9 (differential x − y)
inductive write head connection for
head H9 (differential x − y)
MR-read head connection for head
H9 (differential x − y)
ground connection for head H9
MR-read head connection for head
H9 (differential x − y)
9GND
7GND
7Ry
62
63
0Rx
56
8GND
8Ry
0Wy
7Rx
inductive write head connection for
head H7 (differential x − y)
MR-read head connection for head
H7 (differential x − y)
ground connection for head H7
MR-read head connection for head
H7 (differential x − y)
inductive write head connection for
head H8 (differential x − y)
inductive write head connection for
head H8 (differential x − y)
MR-read head connection for head
H8 (differential x − y)
DESCRIPTION
9Ry
55
SYMBOL PAD
0Wx
7Wy
DESCRIPTION
TDA5155
7
MGG981
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
8
8.1
8.2
FUNCTIONAL DESCRIPTION
Write mode
To minimize power dissipation, the read circuitry may be
disabled in write mode. The write circuitry is disabled in
read, sleep and standby modes. In write mode, a
programmable current is forced through the selected
two-terminal inductive write head. The push-pull output
drivers yield near rail-to-rail voltage swings for fast current
polarity switching.
Read mode
The read mode disables the write circuitry to save power
while reading. The read circuitry is disactivated for write,
sleep and standby modes. The read circuitry may also be
biased during write mode to shorten transients.
The selected head is connected to a multiplexed low-noise
read amplifier. The read amplifier has low-impedance
inputs nRx and nRy (n is the number of the head) and
low-impedance outputs RDx and RDy. The signal polarity
is non-inverting from x and y inputs to x and y outputs.
The write data input can be either voltage or current input
(see Chapter 12). In voltage mode, the differential write
data inputs WDIx(v) and WDIy(v) are PECL (Positive
Emitter Coupled Logic) compatible. The write data flip-flop
can either be used or passed-by. In the case that the write
data flip-flop is used, current polarity is toggled at the
falling edges of
V WDIx ( v ) – V WDIy ( v )
V data = ----------------------------------------------------2
Switching to write mode initializes the data flip-flop so that
the write current flows in the write head from x to y. In the
case that the write data flip-flop is not used, the signal
polarity is non-inverting from x and y inputs to
x and y outputs.
Ambient magnetic fields at the MR elements result in a
relative change in MR resistance:
dR MR
-------------R MR
This change produces a current variation:
dR MR
dI MR = I MR × -------------- ,
R MR
where IMR is the bias current in the MR element.
The current variation is amplified to form the read data
output signal voltage, which is available at RDx and RDy.
AC coupling between MR elements and amplifier stages
prevents the amplifier input stages from overloading by DC
voltages across the MR elements. A fast settling
procedure shortens DC settling transients.
The write current magnitude is controlled through on-chip
DACs. The write current is defined as follows:
10kΩ
I WR = --------------- ( 20 + 16d4 + 8d3 + 4d2 + 2d1 + d0 )
R ext
(in mA), where d4-d0 are bits (either logic 0 or logic 1).
The adjustable range of the write current is 20 mA to
51 mA. At power-up, the default values
d4 = d3 = d2 = d1 = d0 = logic 0 are initialized,
corresponding to IWR = 20 mA. IWR is the current provided
by the write drivers: the current in the write coil and in the
damping resistor together. The static current in the write
coil is
I WR
----------------- ,
R
1 + ------hRd
An on-chip generated stable temperature reference
voltage (1.32 V), available at the Rext pin, is dropped
across an external resistor (10 kΩ) to form a global
reference current for the write and the MR bias currents.
The MR bias current DACs are programmed through the
serial interface according to the following formula:
10kΩ
I MR = 0.5 × --------------- ( 10 + 16d4 + 8d3 + 4d2 + 2d1 + d0 )
R ext
(in mA), where d4-d0 are bits (either logic 0 or logic 1).
At power-up all bits are set to logic 0, which results in a
default MR current of 5 mA. The adjustable range of the
MR currents is 5 mA to 20.5 mA. The MR bias currents are
equal for the two stripes of each head. The gain amplifier
is 1-bit programmable. The amplifier gain can be set to its
nominal value or to the nominal value +3 dB.
1997 Apr 08
TDA5155
where Rh is the resistance of the coil including leads and
Rd is the damping resistor.
8
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
8.3
Three phases in the communication are distinguishable:
addressing, programming and reading. Each
communication sequence starts with an addressing
phase, followed by either a programming phase or a
reading phase.
Sleep mode
In sleep mode, the device is accessible via the serial
interface. All circuits are inactive, except the circuits of the
CMOS serial interface and the circuitry which forces the
data registers to their default values at power-up and
which fixes the DC level of outputs RDx and RDy (required
when operating with more than one amplifier). Typical
static current consumption is −30 µA. Dynamic current
consumption during operation of the serial interface in
sleep mode due to external activity at the inputs to the
serial interface is not included. In all modes, including the
sleep mode, data registers can be programmed. Sleep is
the default mode at power-up. Switching to other modes
takes less than 0.1 ms.
8.4
8.6.1
Standby mode
8.6.2
Active mode
8.6.3
Bi-directional serial interface
READING DATA
Immediately after the IC detects that a7 = logic 1, data
from the data register (address a5 to a0) is copied in
parallel to the input register. Two wait clock cycles must
follow before the controller can start inputting data. At the
first falling edge of SCLK after the 2 wait rising edges of
SCLK, the LSB d0 is placed on SDATA line followed by d1
at the next falling edge of SCLK etc. If SEN goes LOW
before 8 address bits (a7 to a0) have been detected, the
communication is ignored. If SEN goes LOW before the
8 data bits have been sent out of the IC, the reading
sequence is immediately interrupted. See Fig.4 for the
timing diagram of the reading via the serial interface.
The serial interface is used for programming the device
and for reading of status information. 16 bits (8 bits for
data and 8 for address) are used to program the device.
The serial interface requires 3 pins: SDATA, SCLK and
SEN. These pins (and R/W as well) are CMOS inputs.
The logic input R/W has an internal 20 kΩ pull-up resistor
and the SEN logic input has an internal 20 kΩ pull-down
resistor. Thus, in case the SEN line is opened, no data will
be registered and in case the R/W line is opened, the
device will never be in write mode.
SDATA: serial data; bi-directional data interface. In all
circumstances, the LSB is transmitted first.
SCLK: serial clock; 25 MHz clock frequency.
SEN: serial enable; data transfer takes place when SEN is
HIGH. When SEN is LOW, data and clock signals are
prohibited from entering the circuit.
1997 Apr 08
PROGRAMMING DATA
If a7 = 0, the last eight bits d7 to d0 before SEN goes LOW
are shifted into an input register. When SEN goes LOW,
the communication sequence is ended and the data in the
input register is copied in parallel to the data register that
corresponds to the decoded address a0 to a5. SEN
should go LOW at least 5 ns after the last rising edge of
SCLK. See Fig.3 for the timing diagram of the
programming.
Active mode is either read mode or write mode depending
on the status of the R/W pin.
8.6
ADDRESSING
When SEN goes HIGH, bits are latched in at rising edges
of SCLK. The first eight bits a7 to a0 (starting with a0) are
shifted serially into an address register. If SEN goes LOW
before 16 bits have been received, the operation is
ignored. When more than 16 bits (address and data) are
latched in before SEN goes LOW, the first 8 bits are
interpreted as an address and the last 8 bits as data. SEN
should go HIGH at least 5 ns before the first rising edge of
SCLK. Data should be valid at least 5 ns before and after
a rising edge of SCLK. The first six bits a5 to a0 constitute
the register address. Bit a6 is unused. If bit a7 = logic 0,
a PROGRAMMING sequence starts. If bit a7 = logic 1,
READING data from the pre-amplifier can start.
The circuit can be put in standby mode using the serial
interface. In standby mode, the typical DC current
consumption is 330 µA. Transients from standby mode to
active mode are two orders of magnitude shorter than from
sleep mode to active mode. This is important in the case
of cylinder mode operation with multiple amplifiers.
All amplifiers can operate from standby mode and all head
switch times can be kept just as short as in the case of
operation with a single amplifier. Head switch times are
summarized in the switching characteristics.
8.5
TDA5155
9
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
TDA5155
handbook, full pagewidth
SEN
SCLK
SDATA
a0
a1
a2
a3
a4
a5
a6
0
d0
d1
d2
d3
address
d4
d5
d6
d7
data
MGG983
Fig.3 Timing diagram of the write sequence of the serial interface operation (a7 = logic 0).
handbook, full pagewidth
SEN
SCLK
SDATA
a0
a1
a2
a3
a4
address
a5
a6
1
wait
cycles
d0
d1
d2
d3
d4
d5
d6
d7
data
MGG984
Fig.4 Timing diagram of the read sequence of the serial interface operation a7 = logic 1).
1997 Apr 08
10
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
8.7
Operation of the serial interface
8.7.2
The serial interface programming is summarized in
Section 8.7.10.
8.7.1
POWER CONTROL
By default, d1 = d0 = logic 0, the pre-amplifier powers up
in sleep mode. If d1 = logic 0, d0 = logic 1 or d1 = logic 1,
d0 = logic 0 the circuit goes in standby mode.
If d1 = d0 = logic 1, the circuit goes in active mode (read or
write mode depending on the R/W input).
CONFIGURATION
d0:
By default (d0 = logic 0), write data passes from the
write data input via the data flip-flop to the write driver.
The write driver toggles the current in the head at the
falling edges of:
V WDIx ( v ) – V WDIy ( v )
V data = ----------------------------------------------------- or
2
8.7.3
HEAD SELECT
Selection of a wrong head (H10-H15) causes an head
unsafe condition. HUS goes HIGH when in write mode a
wrong head is selected and when d3 in the configuration
register is LOW. When in read mode and a wrong head is
selected, head H0 is therefore selected and if d3 in the
configuration register is LOW, HUS goes LOW.
I WDIx ( i ) – I WDIy ( i )
I data = ---------------------------------------------2
When d0 = logic 1, the write data flip-flop is not used.
The signal polarity is non-inverting from the inputs WDIx
and WDIy to the outputs nWx and nWy.
8.7.4
SERVO WRITE
The circuit is prepared for servo writing. However, the
device will not be guaranteed.
d1:
8.7.5
By default (d1 = logic 0), the pre-amplifier senses PECL
write signals at WDIx(v) and WDIy(v). When
d1 = logic 1, the pre-amplifier senses input write
currents at WDIx(i) and WDIy(i).
TEST
d2 = d1 = d0 = logic 0. The circuit is not in test mode. This
is the default situation.
8.7.5.1
d2:
MR head test
d2 = logic 0, d1 = logic 0, d0 = logic 1. In read mode, the
voltages at Rx and Ry (at the top of the MR elements) of
the selected head are fed to outputs RDx and RDy.
By measuring the output voltages single ended at two
different IMR currents, the MR resistance can be accurately
measured according to the following formula:
V RDx1 – V RDx2
R MRx = -------------------------------------- for the x-side.
I MRx1 – I MRx2
By default (d2 = logic 0), the write current is inhibited
under low supply voltage conditions. The write current
inhibit is made inactive by programming d2 to logic 1.
d3:
By default (d3 = logic 0), in write mode low supply
voltage, open head, and other conditions are monitored
and flagged at HUS. If d3 = logic 1, HUS is LOW in write
mode and HIGH in read mode.
Open head and head short-circuited-to-ground conditions
can therefore be detected.
d4:
The amplifier read gain may be programmed in the
configuration register. By default (d4 = logic 0), the read
gain is typically 160 with RMR = 28 Ω. If d4 = logic 1, the
read amplifier gain is 3 dB higher (226 in this case).
d2 = logic 0, d1 = logic 1, d0 = logic 0. Same as before,
with the difference that IMR2 is fixed to a minimum constant
value of 5 mA. Measuring in the same way as above with
IMR1 > 5 mA, enables the detection of MR elements
shorted together.
d5:
In order to minimize the write-to-read recovery times,
the first stage of the read amplifier may be kept biased
during write mode. By default, (d5 = logic 0) the read
amplifier is powered down during write mode, and the
fast settling procedure is activated after write-to-read
switching. If d5 = logic 1 the read amplifier is kept biased
during write mode, and the fast settling procedure still
occurs if the head is changed or the MR current is
re-programmed.
1997 Apr 08
TDA5155
8.7.5.2
Temperature monitor
d2 = logic 0, d1 = logic 1, d0 = logic 1. The temperature
monitor voltages are connected to RDx and RDy.
The output differential voltage depends on the
temperature according to: dV = −0.00364 × T + 1.7;
0 < T < 140 °C. The temperature may be measured with a
typical precision of 5 °C.
11
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
8.7.5.3
frequency noise. The HF pole can be used in combination
with the HF zero in order to boost the HF gain locally and
yet limit the very high frequency noise enhancement.
Thermal asperity detector
d2 = logic 1, d1 = x, d0 = (0,1). Unlike the above tests, the
thermal asperity detection does not use the RDx and RDy
outputs. Thus, the reader is fully operational. In case a
thermal asperity is detected, it is flagged at the HUS pin.
8.7.8
V th = ( 210 + 560.d0 + 280.d2 ) µV
d0 of test mode register;
d2 of the compensation capacitor register.
8.7.9
SETTLE PULSE
By default (d2 = d1 = d0 = logic 0) the settle pulse has a
nominal duration of 3 µs. Its value can be programmed
from 2.125 µs to 3 µs according to the following formula:
1
t st = 2µs + ------------------------------------------------------------------- µs
( 4.d2 + 2.d1 + 1.d0 + 1 )
The settle pulse is used to shorten the transients during
switching.
WRITE AMPLIFIER PROGRAMMABLE CAPACITORS
By default (d2 = d1 = d0 = logic 0) the programmable
capacitors are zero. These capacitors are used to improve
the performance of the write amplifier according to the
write amplifier output load.
8.7.7
HIGH FREQUENCY GAIN BOOST REGISTER
By default (d3 = d2 = d1 = d0 = logic 0) the high frequency
gain boost is not active.
The gain boost provides a zero which allows to optimize
the bandwidth of the read amplifier and to correct for
attenuation caused by series inductances in the leads
between the MR heads and the read amplifier inputs.
The threshold voltage for the thermal asperity detection is
2-bit programmable. These 2 bits consist of d0 (LSB) of
the test mode register (address = 0xxx0110), and d2 of the
compensation capacitor register (address = 0xxx0111).
8.7.6
TDA5155
HIGH FREQUENCY GAIN ATTENUATOR REGISTER
By default (d3 = d2 = d1 = d0 = logic 0) the high frequency
gain attenuator is not active. The gain attenuator provides
a pole which limits the bandwidth and reduces the high
8.7.10
ADDRESS REGISTERS SUMMARY
ADDRESS REGISTERS(1)
FUNCTION
A7 A6 A5 A4 A3 A2 A1 A0
0
X
X
X
0
0
0
0
configuration register:
d0 = 0: use data flip-flop; d0 = 1: by-pass data flip-flop
d1 = 0: WDI PECL; d1 = 1: current input
d2 = 0: write current inhibit active; d2 = 1: write current inhibit inactive
read mode: d3 = 0: HUS active; d3 = 1: HUS HIGH
write mode: d3 = 0: HUS active; d3 = 1: HUS LOW
d4 = 0: read gain nominal; d3 = 1: read gain +3 dB
d5 = 0: read amplifier OFF during write mode; d5 = 1: read amplifier ON
during write mode
0
X
X
X
0
0
0
1
power control register:
(d1,d0) = (0,0): sleep mode
(d1,d0) = (1,0) or (0,1): standby mode
(d1,d0) = (1,1): active mode (write or read)
0
X
X
X
0
0
1
0
head select register:
(d3,d2,d1,d0) = (0,0,0,0) to (1,0,0,1): H0 to H9
addressing H10 to H15 causes HUS to go HIGH if in write mode and H0 to be
selected if in read mode
1997 Apr 08
12
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
TDA5155
ADDRESS REGISTERS(1)
FUNCTION
A7 A6 A5 A4 A3 A2 A1 A0
0
X
X
X
0
0
1
1
MR current DAC register:
10kΩ
I MR = 0.5 × --------------- ( 10 + 16.d4 + 8.d3 + 4.d2 + 2.d1 + d0 ) mA
R ext
0
X
X
X
0
1
0
0
write current DAC register:
10kΩ
I WR = --------------- ( 20 + 16.d4 + 8.d3 + 4.d2 + 2.d1 + d0 ) mA
R ext
0
X
X
X
0
1
0
1
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)
0
X
X
X
0
1
1
0
test mode register:
(d2,d1,d0) = (0,0,0) = not in test mode
(d2,d1,d0) = (0,0,1) = read head test (IMR1 = IMR2)
(d2,d1,d0) = (0,1,0) = read head test (IMR2 = 5 mA fixed)
(d2,d1,d0) = (0,1,1) = temperature monitor
(d2,d1,d0) = (1,X,d0) = thermal asperity detection, see note 2
Vth = (210 + 560.d0 + 280.d2) µV
0
X
X
X
0
1
1
1
compensation capacitor register:
equivalent differential capacitance = (4.d2 + 2.d1 + 1.d0) × 2 pF
0
X
X
X
1
0
0
0
high frequency gain attenuator register
800 MHz
nominal pole frequency = --------------------------------------------------------------------8.d3 + 4.d2 + 2.d1 + 1.d0
0
X
X
X
1
0
0
1
high frequency gain boost register
800 MHz
nominal zero frequency = --------------------------------------------------------------------8.d3 + 4.d2 + 2.d1 + 1.d0
0
X
X
X
1
0
1
0
settle time register
1
settle time: t st = 2µs + ------------------------------------------------------------------- µs
( 4.d2 + 2.d1 + 1.d0 + 1 )
1
X
X
X
1
1
1
1
device ID register
ID = 8.d3 + 4.d2 + 2.d1 + 1.d0; d3 to d0 are preset to (0,0,1,1)
1
X
X
X
a3
a2
a1
a0
when a7 = 1, data from the register with address a3 to a0 is read out on
SDATA
Notes
1. Unused bits in the registers (indicated by X) are don’t care. Default data, initialized at Power-up, is zero in all
registers. For VCC <2.5 V, the register contents are not guaranteed.
2. Vth programming uses both the test mode register and the compensation capacitor register. d0 in the formula above
is the LSB of the test mode register and d2 is the d2 data bit of the compensation capacitor register.
1997 Apr 08
13
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
8.8
TDA5155
Test mode: HUS is HIGH except when the TAS detector
is ON. If a thermal asperity is detected, HUS goes LOW.
Head unsafe
The HUS pin is an open collector output. Therefore when
the pin is not connected to an external pull-up resistor,
HUS is LOW. HUS pins can be connected together in case
of operation with more than one amplifier. It is used to
detect abnormal or unexpected operation.
Servo write mode: HUS is LOW.
Write mode:
• If in the configuration register d3 = 1, HUS is LOW
• If in the configuration register d3 = 0, HUS goes HIGH
for:
Sleep mode: HUS is HIGH, to permit working with more
than one amplifier.
– Selection of a wrong head (H10 to H15)(1)
Standby mode: HUS is HIGH, to permit working with
more than one amplifier.
– Rext pin open, short-circuited to ground or to VCC
(write current too low or too high)
Read mode:
– Write Data Input frequency too low (WDIx-WDIy)
• If in the configuration register d3 = 1, HUS is HIGH
– Write head Wx, Wy open, Wx or Wy short-circuited to
ground(2)
• If in the configuration register d3 = 0, HUS goes LOW
for:
– Selection of a wrong head (H10 to
– Write driver still left biased while not selected
H15)(1)
– Low VCC and VCC(WD) conditions (write current inhibit
can be active or inactive).
– Rext pin open, short-circuited to ground or to VCC
(read current too low or too high)
The same detector is used for read and write mode.
The write current may be inhibited if d2 = 0 in the
configuration register.
– Low VCC and VCC(WD) conditions. A low supply
voltage detector is placed close to the VCC and
VCC(WD) pins.
The HUS line indicates an unsafe condition as long as the
fault is present, in read mode as well as in write mode.
It indicates again a safe condition only 0.5 µs to 1 µs after
the last fault has disappeared.
Detection of low VCC (main supply): a VCC supply voltage
below 4.0 V ±5% is flagged at the HUS pin. The voltage
detection range is then 4.2 to 3.8 V with an hysteresis of
110 mV ±10%. Detection of low VCC(WD) (write drivers
supply): a fault will be flagged at the HUS pin if VCC(WD)
drops 0.8 V ±10% below VCC. One must be aware that
such a detection is only aimed to warn for a catastrophic
situation. Indeed, VCC(WD) should never be below VCC.
8.9
(1) Head numbers 0 to 9 are correct, 10 to 15 are signalled as
unsafe.
(2) Switching to write mode makes HUS LOW. After the transient
the HUS detection circuitry is activated. The target for the
head open detection time is 15 ns.
HUS survey
HUS
DATA BIT D3
MODE
STATE
0
1
Sleep mode
−
−
HIGH
HIGH
Standby mode
−
−
HIGH
HIGH
Active mode
Read
Write
Read mode
ACTIVE
HIGH
A-test mode(1)
HIGH
HIGH
TAS mode
ACTIVE
ACTIVE
Write mode
ACTIVE
LOW
A-test mode(1)
HIGH
HIGH
Servo mode(2)
LOW
LOW
Notes
1. A-test mode = analog test mode.
2. In servo mode, the performance of the IC is not guaranteed.
1997 Apr 08
14
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
9
TDA5155
LIMITING VALUES
In accordance with the Absolute Maximum Rating System (IEC 134).
SYMBOL
PARAMETER
MIN.
MAX.
UNIT
VCC
supply voltage
−0.5
+6.0
V
VCC(WD)
write driver supply voltage
−0.5
+9.5
V
Vn1
voltage on all pins except VCC(WD), read inputs nRx, nRy −0.5
and write driver outputs nWx, nWy (n = 0 to 9)
+5.5
V
VCC + 0.5
V
V
−
absolute maximum value
Vn2
voltage on write driver outputs nWx, nWy
absolute maximum value
−0.5
+8.8
−
VCC(WD) + 0.5 V
Vn3
voltage on read inputs nRx, nRy
−0.5
+1
V
InGND
ground current (pins nGND)
−
0.1
A
Tstg
storage temperature
−65
+150
°C
Tj
junction temperature
−
150
°C
10 HANDLING
Inputs and outputs are protected against electrostatic discharge in normal handling. However, to be totally safe, it is
desirable to take normal precautions appropriate to handling integrated circuits.
11 THERMAL CHARACTERISTICS
The thermal resistance depends on the flex used. The TDA5155X is shipped in naked dies form.
1997 Apr 08
15
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
TDA5155
12 RECOMMENDED OPERATION CONDITIONS
SYMBOL
PARAMETER
CONDITIONS
VCC
supply voltage
note 1
note 2
MIN.
TYP
MAX.
4.5
−
5.5
UNIT
V
VCC(WD)
write driver supply voltage
VCC
−
8.8
V
VIH
HIGH level input voltage (CMOS)
3.5
−
VCC
V
VIL
LOW level input voltage (CMOS)
0
−
0.8
V
Vi(dif)(p-p)
differential input voltage
(peak-to-peak value)
note 3
0.4
0.7
1.5
V
VIH(PECL)
HIGH level PECL input voltage
note 3
−
2.85
VCC
V
VIL(PECL)
LOW level PECL input voltage
note 3
1.5
2.15
−
V
Ii(dif)(p-p)
differential input current
(peak-to-peak value)
note 4
0.4
0.8
1.0
mA
IIH(dif)
HIGH level differential input current
note 4
−1.4
−1.2
−
mA
IIL(dif)
LOW level differential input current
note 4
−
−0.4
−0.1
mA
Tamb
ambient temperature
0
−
70
°C
Tj
junction temperature
reading
−
−
110
°C
writing (VCC(WD) = 8 V)
−
−
130
°C
15
28
34
Ω
RMR
MR element resistance
∆(RMR)
RMR mismatch
note 5
−
−
4
Ω
Ll(tot)
total lead inductance to the head
in each lead; note 6
−
25
−
nH
Rl(tot)
total lead resistance to the head
in each lead; note 6
−
1.5
−
Ω
VMR
voltage on top of MR elements
note 7
−
−
0.5
V
Vsig(dif)(p-p)
differential MR head input voltage
(peak-to-peak value)
0.4
1
2
mV
Lwh
write head inductance
including lead; note 6
−
0.15
−
µH
Rwh
write head resistance
including lead; note 6
−
10
−
Ω
Cwh
write head capacitance
including lead; note 6
−
tbf
−
pF
Rext
external reference resistor
−
10
−
kΩ
1997 Apr 08
I ref
V ref
= ---------R ext
16
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
4. Same comments for the given values as for the
voltage input mode. The HIGH (respectively LOW)
level input current is defined such that it produces the
same effect at the output of the writer (Wx, Wy) as the
HIGH (resp. LOW) level input voltage.
Notes to the recommended operating conditions
1. A supply by-pass capacitor from VCC to ground or a
low pass filter may be used to optimize the PSRR.
2. The supply voltage VCC(WD) must never be below VCC
in normal mode, and two diode 1.4 V above VCC in
servo mode.
5. The mismatch refers to the resistance of the two
stripes of the same head. This is defined as follows:
∆(RMR) = abs(RMR1 − RMR2).
3. The given values should be interpreted in the way that
the single ended voltage could swing from
0.2 to 0.75 V, and that the common mode voltage
should be such that for any of the two states, the
VIH(PECL) is less than VCC and VIL(PECL) is more than
1.5 V.
PECL voltage swing: a wider peak-to-peak voltage
swing can be used. In that case a current will flow
through the WDI inputs. This current is approximately
WDIx ( v ) – WDIy ( v ) – 1.4
equal to ------------------------------------------------------------------------200
1997 Apr 08
TDA5155
6. These parameters depend on the head model.
The data given in the table are those used for testing.
7. The combination of maximum head resistance, lead
resistance and bias current is not permitted. To avoid
voltage breakthrough between heads and disk, the
voltage over the MR elements is limited by two diode
voltages.
17
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
TDA5155
13 CHARACTERISTICS
VCC = 5.0 V; VCC(WD) = 8 V; VGND = 0 V; Tamb = 25 °C; unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
Read characteristics
IMR
MR current adjust range
Rext = 10 kΩ; 0.5 mA steps
5
−
20.5
mA
∆IMR
tolerance (excluding Rext)
IMR programmed at 10 mA
−
±4
−
%
Gv(dif)
differential voltage gain;
note 1
from head inputs to RDx, RDy;
RMR = 28 Ω; IMR = 10 mA;
f = 20 MHz
d4 = 0
−
160
−
d4 = 1
−
226
−
−
13
−
Ω
Ri(dif)
differential input resistance
IMR = 10 mA
Ci(dif)
differential input
capacitance
−
16
−
pF
THD
total harmonic distortion
−
1
−
%
BL
lower signal gain pass-band −3 dB
edge
−
−
100
kHz
BH
higher signal gain
pass-band edge
without gain boost
(4 nH lead inductance)
−
220
−
MHz
with gain boost
(50 nH lead inductance)
−
170
−
MHz
−3 dB; note 2
F
noise figure
RMR = 28 Ω; IMR = 10 mA;
Tamb = 25 °C; f = 20 MHz
−
3.0
3.2
dB
Virn
input referred noise voltage; RMR = 28 Ω; IMR = 10 mA;
note 3
Tamb = 25 °C; f = 20 MHz
−
0.9
1.0
nV/√Hz
BF(L)
lower noise band edge
(+3 dB)
RMR = 28 Ω; IMR = 10 mA;
Tamb = 25 °C;
no lead inductance
−
−
400
kHz
BF(H)
upper noise band edge
(+3 dB)
RMR = 28 Ω; IMR = 10 mA;
Tamb = 25 °C;
no lead inductance
−
220
−
MHz
αcs
channel separation; note 4
unselected head
−
50
−
dB
PSRR
power supply rejection ratio; f < 1 MHz; IMR = 10 mA
note 5
f < 100 MHz; IMR = 10 mA
−
80
−
dB
−
50
−
dB
f < 1 MHz
−
45
−
dB
f < 100 MHz
−
25
−
dB
CMRR
1997 Apr 08
common mode rejection
ratio; note 5
from nRx-nRy to RDx-RDy RMR
mismatch < 5%
IMR = 10 mA
18
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
SYMBOL
PARAMETER
TDA5155
CONDITIONS
MIN.
DR
rejection ratio of SCLK and
SDATA; note 6
from SCLK, SDATA inputs to the −
RDx-RDy outputs; a 200 mV
(peak-to-peak) signal is applied
to SCLK or SDATA inputs at
25 MHz, and measurement is
performed at RDx-RDy
VO(R)(dif)
output DC offset voltage in
read mode (differential
after DC settling)
DC voltage between RDx and
RDy
Zo(R)
output impedance in read
mode
single ended
Io(max)(dif)
maximum differential
output current
Vo(cm)
common mode output
voltage in read mode
∆V o ( cm )
---------------------∆V CC
Zo(n)(dif)
TYP.
MAX.
UNIT
50
−
dB
−
−
±0.2
V
−
16
−
Ω
−
4
−
mA
1.0
1.5
2.0
V
common mode DC supply
rejection ratio in read mode
−
20
−
dB
differential output
impedance in other modes
(write, standby, sleep)
−
50
−
kΩ
RDx, RDy
Write characteristics
IWR
write current adjust range
(in the write drivers)
Rext = 10 kΩ; 1 mA steps
20
35
51
mA
∆IWR
tolerance (excluding Rext)
IWR programmed at 35 mA
−
±7
−
%
Vs(max)(p-p)
maximum voltage swing
(peak-to-peak value)
VCC(WD) = 5 V
−
−
8
V
VCC(WD) = 8 V (differential)
−
−
13
V
−
200
−
Ω
−
5
−
pF
VCC(WD) = 8.0 V
−
−
1.8
ns
VCC(WD) = 6.5 V
−
−
2.1
ns
Ro(dif)
differential output
resistance
Co(dif)
differential output
capacitance
not including the head
capacitance
tr, tf
write current rise/fall time
without flip-flop
(10% to 90%); note 7
Lh = 150 nH; Rh = 10 Ω;
IWR = 35 mA; f = 20 MHz
tas
write current rise/fall time
asymmetry; note 8
percentage of tr or tf (tr or tf and
logic asymmetry)
−
−
5
%
tpd
propagation delay 50% of
(WDIx/WDIy) to 50% of
(Wx, Wy)
write head short-circuited, data
flip-flop by-passed
−
−
5
ns
αcs
channel separation
not-selected head
−
45
−
dB
1997 Apr 08
19
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
SYMBOL
PARAMETER
TDA5155
CONDITIONS
MIN.
TYP.
MAX.
UNIT
Switching characteristics
fSCLK
serial interface clock rate
−
−
25
MHz
∆Vo(cm)
common mode DC output
IMR = 10 mA; IWR = 35 mA
voltage change from read to
write mode
−
200
−
mV
trec(W-R)
write-to-read recovery time
(AC and DC settling);
note 9
read amplifier OFF: d5 = 0
−
3
4.5
µs
read amplifier ON: d5 = 1
−
100
150
ns
from 50% of the rising edge of
R/W to steady state read-back
signal: AC and DC settling at
90% (without load at RDx, RDy)
tsw(R)
head switching (in read
mode), standby to read
active and MR current
change recovery time.
(AC and DC settling);
note 10
from falling edge of SEN to
steady state read-back signal
(without load at RDx, RDy)
−
3
4.5
µs
toff(R)
read amplifier off time
from falling edge of R/W to read
head inactive
−
−
50
ns
tst(W)
write settling times; note 11
from 50% of the falling edge of
R/W to 90% of the steady state
write current (in write mode)
−
−
70
ns
toff(W)
write amplifier off time
from rising edge of R/W to
10 × IWR (programmed)
(IWR = 35 mA)
−
−
50
ns
tsw(W)
head switching (in write
from falling edge of SEN to write −
mode), and standby to write head active
head active
50
70
ns
tsw(S)
switch time to and from
sleep mode
−
−
100
µs
−
72
80
mA
from VCC (5 V)
−
33
41
mA
from VCC(WD) (5 to 8 V)
−
54
61
mA
−
0.25
1
mA
−
−0.02
−
mA
−
1.32
−
V
1⁄
DC characteristics
ICC(R)
read mode supply current
IMR = 10 mA; note 12
ICC(W)
write mode supply current
IWR = 35 mA; note 13
IDD(STB)
standby mode supply
current
IDD(S)
sleep mode supply current
Vref
reference voltage for Rext
1997 Apr 08
static
20
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
Notes to the characteristics
5.
1. The differential voltage gain depends on the MR
resistance. It can be improved by programming the
d4 bit in the configuration register.
The PSRR (in dB) is defined as input referred ratio:
Gv
PSRR = 20 × log ------- , where Gv is the differential input
Gp
to differential output gain, and Gp is the power supply
to differential output gain.The CMRR (in dB) is defined
Gv
as input referred ratio: CMRR = 20 × log ----------- , where
G cm
2. The gain boost implements a pole-zero combination:
The +3 dB gain boost corner frequency is
800 MHz
--------------------------------------------------------------------- . The −3 dB gain
8.d3 + 4.d2 + 2.d1 + 1.d0
attenuation corner frequency is
800 MHz
--------------------------------------------------------------------- , where d3, d2, d1 and d0
8.d3 + 4.d2 + 2.d1 + 1.d0
are to be programmed via the serial interface. In
practical use, the bandwidth is limited by the
inductance of the connection between the MR heads
and the pre-amplifier.
Gv is the differential input to differential output gain and
Gcm is the common mode input to differential output
gain. Flex and board lay-out may affect these
parameters significantly.
6. This refers to the crosstalk from SCLK and SDATA
inputs via the read inputs to RDx and RDy. Two cases
can be distinguished:
a) When SEN is LOW, SCLK and SDATA are
prohibited reaching the device and crosstalk is low.
3. Noise calculation
a) Definitions: The amplifier has a low input
resistance. No lead resistance is taken into
account. The input referred noise voltage,
excluding the noise of the MR resistors, is defined
V no 2
2
as: ( V irn ) = --------- – 4kT × ( R MR1 + R MR2 ) ,
Gv
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 to avoid
crosstalk via this path.
7. The rise and fall times depend on the
write amplifier/write head combination. Lh and Rh
represent the components on the evaluation board.
Parasitic capacitances also limit the performance.
where Gv is the voltage gain, Vno is the noise
voltage at the output of the amplifier, k is the
Boltzmann constant and T is the temperature in K.
The noise figure is defined as follows:
V no 2




--------G


v
F = 10 × log  ------------------------------------------------------------ in 1 Hz
4kT
×
(
R
+
R
)
MR1
MR2 



8. The write current rise/fall time asymmetry is defined by
tr – tf
----------------------2 ( tr + tf)
9. Write-to-read recovery time includes the write mode to
read mode switching using the R/W pin on the same
head (see Fig.5). The AC signal reaches its full
amplitude few tens of ns after appearing at the reader
RDx and RDy outputs.
bandwidth. Note that RMR includes all resistances
between Rx or Ry to ground.
b) Noise figure versus IMR and RMR: Table 1 shows
the variation of the noise figure with IMR and RMR.
10. In read mode, the head switching, standby to read
active switching and changing MR current include fast
current settling (see Fig.5). The AC signal reaches its
full amplitude few tenth of ns after appearing at the
reader RDx and RDy outputs.
c) Input referred noise voltage: The input referred
noise voltage calculation can be significantly
different (from 1.0 to 0.44 nV/√Hz for instance) by
taking an equivalent signal-to-noise ratio into
account when using two MR stripes (28 Ω for each
stripe) or one MR stripe (42 Ω). It assumes that the
signal coming from the head is larger for a
dual-stripe head than for a single-stripe head (50%
extra signal for a dual-stripe head).
11. Write settling time includes the read mode to write
mode switching using the R/W pin.
12. The typical supply current in read mode depends on
the bias current for the MR element.
13. The typical supply current in write mode also depends
on the write current.
4. The channel separation is defined by the ratio of the
gain response of the amplifier using the selected head
H(n) to the gain response of the amplifier using the
adjacent head H(n ±1), head H(n) being selected.
1997 Apr 08
TDA5155
21
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
Table 1
TDA5155
Noise figure
F (dB)
RMR (Ω)
IMR = 7 mA
IMR = 10 mA
IMR = 15 mA
20
2.7
2.9
3.1
25
2.8
3.0
3.3
30
2.9
3.1
3.5
handbook, full pagewidth
R/W
RDx-RDy
trec(W-R)
toff(R)
MGG985
Fig.5 Timing diagram of the reader: write-to-read switching on the same logic head.
handbook, full pagewidth
SEN
RDx-RDy
tsw(R)
MGG986
Fig.6 Timing diagram of the reader: typical head, current and standby-to-read characteristics.
1997 Apr 08
22
Philips Semiconductors
Preliminary specification
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
TDA5155
14 DEFINITIONS
Data sheet status
Objective specification
This data sheet contains target or goal specifications for product development.
Preliminary specification
This data sheet contains preliminary data; supplementary data may be published later.
Product specification
This data sheet contains final product specifications.
Limiting values
Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one or
more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation
of the device at these or at any other conditions above those given in the Characteristics sections of the specification
is not implied. Exposure to limiting values for extended periods may affect device reliability.
Application information
Where application information is given, it is advisory and does not form part of the specification.
15 LIFE SUPPORT APPLICATIONS
These products are not designed for use in life support appliances, devices, or systems where malfunction of these
products can reasonably be expected to result in personal injury. Philips customers using or selling these products for
use in such applications do so at their own risk and agree to fully indemnify Philips for any damages resulting from such
improper use or sale.
1997 Apr 08
23
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© Philips Electronics N.V. 1997
SCA54
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Printed in The Netherlands
297027/20/01/pp24
Date of release: 1997 Apr 08
Document order number:
9397 750 01427