MAX4951
Detailed Description
The MAX4951 consists of two identical buffers that take
SATA input signals and return them to full output levels.
This device functions up to 6.0Gbps for next-generation
SATA applications.
Input/Output Terminations
Inputs and outputs are internally 50Ω terminated to V
CC
(see the
Functional Diagram/Truth Table
) and must be
AC-coupled to the SATA controller IC and SATA device
for proper operation.
Out-Of-Band Logic
The MAX4951 provides full Out-Of-Band (OOB) signal
support through high-speed amplitude detection cir-
cuitry. SATA OOB differential input signals of 50mV
P-P
or less are detected as OFF and not passed to the out-
put. This prevents the system from responding to
unwanted noise. SATA OOB differential input signals of
150mV
P-P
or more are detected as ON and passed to
the output. This allows OOB signals to transmit through
the MAX4951. The time for the amplitude detection cir-
cuit to detect an inactive SATA OOB input and squelch
the associated output, or detect an active SATA OOB
input and enable the output, is less than 5ns.
Enable Input
The MAX4951 features an active-high enable input (EN).
EN has an internal pulldown resistor of 70kΩ (typ). When
EN is driven low or left unconnected, the MAX4951
enters low-power standby mode and the buffers are dis-
abled. Drive EN high for normal operation.
Output Boost Selection Inputs
The MAX4951 has two digital control logic inputs, BA
and BB. BA and BB have internal pulldown resistors of
70kΩ (typ). BA and BB control the boost level of their
corresponding buffers (see the
Functional Diagram/
Truth Table
). Drive BA or BB low or leave unconnected
for standard SATA output levels. Drive BA or BB high to
boost the output. The boosted output level compen-
sates for attenuation from longer trace-length cables or
to meet eSATA specifications.
Applications Information
Figure 3 shows a typical application circuit with the
MAX4951 used to drive an eSATA output. The diagram
assumes that the MAX4951 is close to the SATA host
controller. BB is set low to drive standard SATA levels
to the host, and BA is set high to drive eSATA levels to
the device. If the MAX4951 is further from the controller,
set BB high to compensate for attenuation.
SATA I/SATA II Bidirectional Re-Driver
6 _______________________________________________________________________________________
Pin Description
Positive Supply Voltage Input. Bypass V
close to the device as possible.
Active-High Enable Input. Drive EN low to put device in standby mode. Drive EN high for normal operation.
EN is internally pulled down.
Channel-B Boost Enable Input. Drive BB high to enable channel-B output boost. Drive BB low for standard
SATA output level. BB is internally pulled down.
Channel-A Boost Enable Input. Drive BA high to enable channel-A output boost. Drive BA low for standard
SATA output level. BA is internally pulled down.
Exposed Pad. Internally connected to GND. EP must be electrically connected to a ground plane for proper
thermal and electrical operation.
