GS6150 Datasheet, PDF (23/64 Pages) Gennum Corporation – Automatic or Manual Rate Selection

4.3.4 Low/High Bit Rate Detection for Slew Rate Control
A status output named LBR_HBR is provided to control the slew rate selection input of
a downstream SDI cable driver. It can be connected to the SD_EN input of drivers such
as the GS6080 or GS6081 using the Semtech recommended application circuit.
When this signal is HIGH, the data rate is 270Mb/s (SD) or 125Mb/s (MADI). This signal is
LOW for all other supported data rates, and when the GS6150 is operating in Bypass
Mode or any time the device is not locked.
The LBR_HBR output signal is available to the application on any of the GPIO[3:0]
multifunction status and control pins. It is selected for output using the
GPIO[3:0]_IO_SELECT and GPIO[3:0]_SELECT bits accessible in the
GPIO_CONTROL_REG_0 and GPIO_CONTROL_REG_1 registers. By default, LBR_HBR is
output on GPIO2.
4.4 Low Power Modes
The device can be programmed via the GSPI to operate in two different low power
modes. SLEEP mode has minimum power consumption at the expense of recovery time
upon de-assertion of the FORCE_PWRDN_SLEEP bit. STANDBY mode has higher power
consumption relative to SLEEP mode but minimizes time to return to operation on de-
assertion of the FORCE_PWRDN_STANDBY bit. The features affected by each mode are
outlined below.
SLEEP mode:
• LOS detection remains functional
• The GSPI remains functional
• The reference oscillator remains functional
STANDBY mode:
• LOS detection remains functional
• The GSPI remains functional
• The reference oscillator remains functional
• The VCO and PLL remains functional so as to minimize the lock time when a signal is detected
• The rate detector remains set to the last valid data rate. On detection of a signal, the
last valid rate is tested first by the rate detect state machine
The device can be programmed to automatically enter into SLEEP or STANDBY mode
when LOS is asserted by programming the AUTO_PWRDN_DISABLE bit in the
PWRDN_CONTROL register at address 17_h. The AUTO_PWRDN_MODE bit in the same
register selects which mode, SLEEP or STANDBY, is entered into upon assertion of LOS.
GS6150
Final Data Sheet
PDS-060127
Rev.2
March 2015
www.semtech.com
23 of 64
Proprietary & Confidential