LMH2190 Datasheet, PDF (19/24 Pages) National Semiconductor (TI) – Quad Channel 27 MHz Clock Tree Driver with I2C Interface

TABLE 4. CLK2 Output Register
Address = 02H, type = R/W, reset value = 06H, 0000_0110, Bold face settings are the default configuration.
Field
Bits Description
CLK2 Load
[1-0]
Sets the drive strength of the clock output based on the capacitive load.
00 - 10pF to 15pF
01 - 15pF to 22.5pF
10 - 22.5pF to 33.5pF
11 - 33.5pF to 50pF
CLK_REQ2 Input Polarity
[2] Sets whether a logic low or high enables the clock output.
0 - Logic low enables the clock output.
1 - Logic high enables the clock output.
CLK_REQ2 Force ON Control
[3] Selects whether to use a clock request or I²C logic to enable the output.
0 - Use the clock request pin to control the output.
1 - Force the clock output to be enabled (Force ON).
CLK_REQ2 Force OFF Control
[4] Selects whether to use a clock request or I²C logic to disable the output.
0 - Use the clock request pin to control the output.
1 - Force the clock output to be disabled (Force OFF). ”Force OFF" overrides ”Force
ON".
CLK_REQ2 Pull down Resistor
[5] Selects whether an internal 200 kΩ pull down resistor on the clock request input to GND
is present.
0 - No internal pull down resistor is present.
1 - Internal 200 kΩ pull-down resistor is present.
Reserved
[6]
Reserved
[7]
TABLE 5. CLK3 Output Register
Address = 03H, type = R/W, reset value = 06H, 0000_0110, Bold face settings are the default configuration.
Field
Bits Description
CLK3 Load
[1-0]
Sets the drive strength of the clock output based on the capacitive load.
00 - 10pF to 15pF
01 - 15pF to 22.5pF
10 - 22.5pF to 33.5pF
11 - 33.5pF to 50pF
CLK_REQ3 Input Polarity
[2] Sets whether a logic low or high enables the clock output.
0 - Logic low enables the clock output.
1 - Logic high enables the clock output.
CLK_REQ3 Force ON Control
[3] Selects whether to use a clock request or I²C logic to enable the output.
0 - Use the clock request pin to control the output.
1 - Force the clock output to be enabled (Force ON).
CLK_REQ3 Force OFF Control
[4] Selects whether to use a clock request or I²C logic to disable the output.
0 - Use the clock request pin to control the output.
1 - Force the clock output to be disabled (Force OFF). ”Force OFF" overrides ”Force
ON".
CLK_REQ3 Pull down Resistor
[5] Selects whether an internal 200 kΩ pull down resistor on the clock request input to GND
is present.
0 - No internal pull down resistor is present.
1 - Internal 200 kΩ pull-down resistor is present.
Reserved
[6]
Reserved
[7]
19
www.national.com