tda5155 NXP Semiconductors, tda5155 Datasheet - Page 14

• Manufacturer Part Number: tda5155
• Description: Pre-amplifier For Hard Disk Drive Hdd With Mr-read/inductive Write Heads
• Manufacturer: NXP Semiconductors

Philips Semiconductors
8.8
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.
Sleep mode: HUS is HIGH, to permit working with more
than one amplifier.
Standby mode: HUS is HIGH, to permit working with
more than one amplifier.
Read mode:
Detection of low V
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 V
supply): a fault will be flagged at the HUS pin if V
drops 0.8 V 10% below V
such a detection is only aimed to warn for a catastrophic
situation. Indeed, V
8.9
Notes
1. A-test mode = analog test mode.
2. In servo mode, the performance of the IC is not guaranteed.
1997 Apr 08
If in the configuration register d3 = 1, HUS is HIGH
If in the configuration register d3 = 0, HUS goes LOW
for:
– Selection of a wrong head (H10 to H15)
– R
– Low V
Pre-amplifier for Hard Disk Drive (HDD)
with MR-read/inductive write heads
(read current too low or too high)
voltage detector is placed close to the V
V
CC(WD)
ext
Head unsafe
HUS survey
pin open, short-circuited to ground or to V
CC
Standby mode
Active mode
Sleep mode
pins.
and V
MODE
CC
CC(WD)
CC(WD)
(main supply): a V
should never be below V
CC
conditions. A low supply
. One must be aware that
CC(WD)
HUS
CC
(write drivers
supply voltage
(1)
Read
Write
CC
and
CC(WD)
CC
CC
.
STATE
14
A-test mode
A-test mode
Servo mode
Test mode: HUS is HIGH except when the TAS detector
is ON. If a thermal asperity is detected, HUS goes LOW.
Servo write mode: HUS is LOW.
Write mode:
The same detector is used for read and write mode.
The write current may be inhibited if d2 = 0 in the
configuration register.
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 s to 1 s after
the last fault has disappeared.
(1) Head numbers 0 to 9 are correct, 10 to 15 are signalled as
(2) Switching to write mode makes HUS LOW. After the transient
Read mode
Write mode
TAS mode
If in the configuration register d3 = 1, HUS is LOW
If in the configuration register d3 = 0, HUS goes HIGH
for:
– Selection of a wrong head (H10 to H15)
– R
– Write Data Input frequency too low (WDIx-WDIy)
– Write head Wx, Wy open, Wx or Wy short-circuited to
– Write driver still left biased while not selected
– Low V
unsafe.
the HUS detection circuitry is activated. The target for the
head open detection time is 15 ns.
(write current too low or too high)
ground
can be active or inactive).
ext
pin open, short-circuited to ground or to V
CC
(1)
(1)
(2)
(2)
and V
CC(WD)
ACTIVE
ACTIVE
ACTIVE
HIGH
HIGH
HIGH
HIGH
LOW
0
conditions (write current inhibit
DATA BIT D3
Preliminary specification
TDA5155
ACTIVE
HIGH
HIGH
HIGH
HIGH
HIGH
(1)
LOW
LOW
1
CC