TDA5153 Datasheet, PDF (16/28 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
8.11 Head unsafe
The HUS pin is an open-collector output. Consequently,
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/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:
• if in the configuration register d3 = 1, HUS is HIGH
• if in the configuration register d3 = 0, HUS goes LOW
for:
– R_ext pin open, short-circuited to ground or to V_CC
(read current too low or too high)
– Low V_CC and V_CC(WD) conditions. A low supply
voltage detector is placed close to the V_CC and
V_CC(WD) pins.
Detection of low V_CC (main general supply): a V_CC supply
voltage below 4.0 V ±5% is flagged to 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_CC(WD)
(writer dedicated supply): a fault will be flagged at HUS pin
if V_CC(WD) drops 0.8 V ±10% below V_CC. One must be
aware that such a detection is only aimed to warn for a
catastrophic situation. Indeed, V_CC(WD) should never be
below V_CC.
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:
• if in the configuration register d3 = 1, HUS is LOW
• if in the configuration register d3 = 0, HUS goes HIGH
for: the write current may be inhibited if d1 = 0 in the
configuration register.
– R_ext pin open, short-circuited to ground or to V_CC
(write current too low or too high)
– Write data input frequency too low (WDIx − WDIy)
– Write head Wx − Wy open, Wx or Wy short-circuited
to ground (switching to write mode makes HUS LOW;
after the transient the HUS detection circuitry is
activated; the target for the head-open detect time is
15 ns)
– Write-head still left biased while not selected
– Low V_CC and V_CC(WD) conditions (write current inhibit
can be active or inactive).
The same detector is used for read and write mode. HUS
goes LOW again between 0.5 and 1 µs after the last
unsafe condition was detected.
8.12 HUS survey
MODE
Sleep mode
Standby mode
Active mode
HUS
−
−
Read
Write
STATE
−
−
Read mode
A-test mode⁽¹⁾
TAS mode
Write mode
A-test mode⁽¹⁾
Servo mode⁽²⁾
Notes
1. HUS survey: A-test mode = analog test mode.
2. In servo mode, the performance of the IC is not guaranteed.
DATA BIT D3
0
1
HIGH
HIGH
ACTIVE
HIGH
ACTIVE
ACTIVE
HIGH
LOW
HIGH
HIGH
HIGH
HIGH
ACTIVE
LOW
HIGH
LOW
1997 Jul 02
16