SBAA808 April   2026 SN74HC00 , SN74HC00-Q1 , SN74HC02 , SN74HC02-Q1 , SN74HC04 , SN74HC04-Q1 , SN74HC08 , SN74HC08-Q1 , SN74HC10 , SN74HC10-Q1 , SN74HC125 , SN74HC125-Q1 , SN74HC126 , SN74HC132 , SN74HC132-Q1 , SN74HC138 , SN74HC138-Q1 , SN74HC139 , SN74HC139-Q1 , SN74HC14 , SN74HC14-Q1 , SN74HC151 , SN74HC151-Q1 , SN74HC153 , SN74HC157 , SN74HC164 , SN74HC165 , SN74HC165-Q1 , SN74HC174 , SN74HC175 , SN74HC20 , SN74HC240 , SN74HC244 , SN74HC244-Q1 , SN74HC245 , SN74HC259 , SN74HC273 , SN74HC273-Q1 , SN74HC32 , SN74HC365 , SN74HC367 , SN74HC373 , SN74HC374 , SN74HC393 , SN74HC4040 , SN74HC541 , SN74HC573 , SN74HC574 , SN74HC594 , SN74HC595 , SN74HC646 , SN74HC688 , SN74HC74 , SN74HC74-Q1 , SN74HC86 , SN74HC86-Q1 , SN74HCS00 , SN74HCS00-Q1 , SN74HCS02 , SN74HCS02-Q1 , SN74HCS08 , SN74HCS08-Q1 , SN74HCS125 , SN74HCS125-Q1 , SN74HCS138 , SN74HCS138-Q1 , SN74HCS14 , SN74HCS14-Q1 , SN74HCS151 , SN74HCS151-Q1 , SN74HCS153 , SN74HCS153-Q1 , SN74HCS157 , SN74HCS157-Q1 , SN74HCS164 , SN74HCS164-Q1 , SN74HCS165 , SN74HCS165-Q1 , SN74HCS259 , SN74HCS259-Q1 , SN74HCS32 , SN74HCS32-Q1 , SN74HCS365 , SN74HCS365-Q1 , SN74HCS367 , SN74HCS367-Q1 , SN74HCS594 , SN74HCS594-Q1 , SN74HCS595 , SN74HCS595-Q1 , SN74HCS74 , SN74HCS74-Q1

 

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  3.   Trademarks

Why do we need to use linear interpolation?

Some logic families, such as the HC and HCS families, specify parameters only at supply voltages of 2V, 4.5V, and 6V. As most systems operate logic devices at 1.8V, 3.3V, or 5V supply voltages, designers working with these or similar families often need to use linear interpolation to determine various performance specifications at the appropriate supply voltage. Linear interpolation of data sheet tables can be used to determine minimum and maximum performance specifications specified by the datasheet. Linear interpolation can also be used to estimate typical performance values at any VCC voltage within the minimum and maximum VCC range provided by the recommended operating conditions.

Example Calculation

Let's determine the minimum VIH and maximum VIL values of the SN74HC595 at 3.3V VCC. VIH and VIL are provided in the Recommended Operation Conditions table of the datasheet, which is provided in SN74HC595 Recommended Operating Conditions.

SN74HC595 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)(1)
SN54HC595 SN74HC595 UNIT
MIN NOM MAX MIN NOM MAX
VCC Supply voltage 2 5 6 2 5 6 V
VIH High-level input voltage VCC = 2V 1.5 1.5 V
VCC = 4.5V 3.15 3.15
VCC = 6V 4.2 4.2
VIL Low-level input voltage VCC = 2V 0.5 0.5 V
VCC = 4.5V 1.35 1.35
VCC = 6V 1.8 1.8
VI Input voltage 0 VCC 0 VCC V
VO Output voltage 0 VCC 0 VCC V
Δt/Δv Input transition rise or fall time(2) VCC = 2V 1000 1000 ns
VCC = 4.5V 500 500
VCC = 6V 400 400
TA Operating free-air temperature –55 125 –40 85 °C
(1) All unused inputs of the device must be held at VCC or GND to verify proper device operation. See the TI application report, Implications of Slow or Floating CMOS Inputs, SCBA004.
(2) If this device is used in the threshold region (from VILmax = 0.5V to VIH min = 1.5V), there is a potential to go into the wrong state from induced grounding, causing double clocking. Operating with the inputs at tt = 1000ns and VCC = 2V does not damage the device; however, functionally, the CLK inputs are not verified while in the shift, count, or toggle operating modes.

The minimum VIH is given as 1.5V at VCC = 2V and 3.15V at VCC = 4.5V. For the minimum VIH at 3.3V VCC, we can interpolate between these two data points as follows: V IH  (VCC = 3.3 V)  = 1.5 + 3.3 - 2 × 3.15 - 1.5 4.5 - 2 = 1.5 + 3.3 - 2 × 1.65 2.5 = 2.358  V.

Similarly, the maximum VIL is given as 0.5V at VCC = 2V and 1.35V at VCC = 4.5V. For the maximum VIL at 3.3V VCC, we calculate: V IL  (VCC = 3.3 V)  = 0.5 + 3.3 - 2 × 1.35 - 0.5 4.5 - 2 = 0.5 + 3.3 - 2 × 0.85 2.5 = 0.942  V.