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RE: LMH0384 Input Level Specs

khoi nguyen
Prodigy 30 points
Other Parts Discussed in Thread: LMH0384

Hi Michael,

I have the following question below regarding the Input LEVEL specs for the LMH0384. I've pasted the specs below (not sure if it can be viewed nicely).

From the datasheet the a VIH ranges from 2V to Vcc, whereas a VIL is from VEE to 0.8V. Also, the Common-mode is 1.75V and the voltage swing typically is 800mV at the input.

My question is the following:

If the common mode is 1.75V and the swing is 800mV peak-to-peak, would this mean the VIL is at 1.75 - (800mV/2), which is only 1.35V is not low enough to qualify for a VIL?

Thanks,

khoi

6.5 DC Electrical Characteristics
Over Supply Voltage and Operating Temperature ranges, unless otherwise specified.
(1)(2)(3)(4)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VIH Input Voltage High Level (Logic Inputs) 2 VCC V
VIL Input Voltage Low Level VEE 0.8 V
VSDI Input Voltage Swing (SDI, SDI) 0 m cable length
(5)
720 800 950 mVP−P
VCMIN Input Common-Mode Voltage (SDI, SDI) 1.75 V

  • 0
    TI__Mastermind 29655 points
    Hi Khoi,

    There are two different types of inputs, logic and SDI analog signals.

    The two parameters you referenced first, VIH and VIL, apply to LVCMOS logic level pins such as SPI_EN and SS#.

    Those pins are different from the SDI and SDI# pins. The VIH and VIL parameters do not apply to the SDI inputs. In contrast, the input voltage swing and common-mode voltage apply to the SDI inputs. According to this definition, the expected input levels are nominally 1.75 + (0.8/2) V and 1.75 - (0.8/2) V.

    Michael