SN74HCT245: current drive capability

[FAE] Andrew Wang

Part Number: SN74HCT245

Hi Team,

Customer is using SN74HCT245 to drive opto-coupler, the estimated current for driving is about 10mA max, can HCT245 support it? how much VOH would drop? Thanks!

Andrew

over 6 years ago

0 Emrys Maier over 6 years ago

TI__Guru* 96862 points

Hello Andrew,
This device can support 10mA continuous output current (from abs max table: Io (max) = 35mA).

Using the provided datasheet values, we can calculate r_on for the output FET: r_on = (V_CC-V_OH)/I_OH = 110 ohms

Then ohm's law gives the maximum voltage drop at 10 mA --> V = I*R = 110*0.010 = 1.1V. V_OH(min @ 10mA) = Vcc - 1.1V

0 [FAE] Andrew Wang over 6 years ago in reply to Emrys Maier

TI__Genius 10685 points

Thanks for detail feedback, very useful!!

Andrew

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SN74HCT245: current drive capability