RSTI
¯¯¯¯
The RSTI
¯¯¯¯ push button switch controls RSTI
¯¯¯¯ , and the RSTI
¯¯¯¯ LED shows its state. RSTI
¯¯¯¯ is used to reset the cable
driver to its default register settings. The RSTI
¯¯¯¯ LED is Green during normal operation (RSTI
¯¯¯¯ = 1), and Red when
the cable driver is held in reset (RSTI
¯¯¯¯ = 0). To reset the device, the RSTI
¯¯¯¯ switch must be pushed twice to fully
toggle reset: once to put the device in reset mode (RSTI
¯¯¯¯ = 0), and again to resume normal operation (RSTI
¯¯¯¯ = 1)
with the default register settings.
RSTO
¯¯¯¯¯
The RSTO
¯¯¯¯¯ LED shows the state of RSTO
¯¯¯¯¯ . The RSTO
¯¯¯¯¯ LED is normally Red to indicate RSTO
¯¯¯¯¯ = 0. RSTO
¯¯¯¯¯ is the
reset output used when daisy chaining multiple cable drivers on the same SMBus. After writing a new device
address to register 00h (the ID register), the RSTO
¯¯¯¯¯ LED changes to Green to indicate RSTO
¯¯¯¯¯ = 1. RSTO
¯¯¯¯¯ remains
high until the device is reset with RSTI
¯¯¯¯ .
Termination Faults (TFxx)
The Termination Fault LEDs show the state of the Termination Faults on the cable driver outputs. The Termination
Fault LEDs are Green to indicate proper termination, Red to indicate improper or missing termination, and off to
indicate the Termination Faults are not valid under the current cable driver conditions.
The cable driver must be enabled and must have a valid input signal in order to properly detect cable termination
on the output. If no signal is detected and the LOS
¯¯¯¯ LED is Red, then the Termination Fault detectors (TF1P, TF1N,
TF0P, and TF0N for the LMH0307) cannot determine the state of the output termination and the LEDs will be off.
When a valid input signal is applied, the Termination Fault detectors will show the correct state of their termination.
If the cable driver is disabled or if the output channel is powered down, the Termination Fault LEDs will be off.
LOS
¯¯¯¯
The LOS
¯¯¯¯ LED shows the status of the input signal detector. The LOS
¯¯¯¯ LED is Green to indicate a valid input
signal ( LOS
¯¯¯¯ = 1), and Red when no signal is detected (LOS
¯¯¯¯ = 0). When the cable driver is disabled (ENABLE = 0),
the LOS
¯¯¯¯ detection is disabled as well and the LOS
¯¯¯¯ LED will be Red to indicate no signal can be detected. If the
LOS
¯¯¯¯ LED is Red, then the Termination Fault detection does not function and the TFxx LEDs are forced off.
With the LOSEN register bit (bit 4 of register 05h) set, the LOS
¯¯¯¯ detection may still function while the cable driver is
disabled. In this mode, LOS
¯¯¯¯ is combined with the ENABLE functionality, and if the input signal is removed then the
cable driver will power down but keep the LOS
¯¯¯¯ detection running. The device will power back on once an input
signal is detected. (While in this mode, disabling the device by pushing the ENABLE switch will still power down
the device completely, including powering down Termination Fault and LOS
¯¯¯¯ detection).
LEDs and Push Button Switches Summary
Table 2 shows a summary of the LEDs provided to assist the user in determining the configuration of the board,
and Table 3 shows a summary of the push button switches provided to allow control of the board functions.
SD303/SD307 EVK User Guide
4 of 27
Rev 1.2
© 2010, National Semiconductor Corp.
