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I understand that "drive output" on this datasheet means that it's the maximum current the IC can source/sink - i.e. if there is something pulling one of its outputs high at a current higher than 6mA, it cant pull the output low. This is, at least, what seems to be happening. If i put a 3.3kohm pull-up resistor on an output (to make it default to high when OE is high), the shift register cant seem to pull it low when OE is low. If I put a second resistor to get 6.6kohm, it can pull the output low. I'm measuring that it can't pull the resistor low by connecting each output to the segments of a 7 segment display. When the shift register pulls them high, the segments get brighter, but when it (should try to) pull them low, they dont turn off or get dimmer. They do turn off when I use two resistors though. But theres a problem there - I'm supplying it 3.3v, so the single pull-up resistor (to a 3.3v source) should only be pulling 1mA, which is less than the "drive output" on the datasheet, so the shift register should be able to pull it low. Am I misunderstanding the datasheet or is something else going on here?

^{simulate this circuit – Schematic created using CircuitLab}

I understand that "drive output" on this datasheet means that it's the maximum current the IC can source/sink - i.e. if there is something pulling one of its outputs high at a current higher than 6 mA, it cant pull the output low. This is, at least, what seems to be happening. If I put a 3.3 kΩ pull-up resistor on an output (to make it default to high when OE is high), the shift register cant seem to pull it low when OE is low. If I put a second resistor to get 6.6 kΩ, it can pull the output low. I'm measuring that it can't pull the resistor low by connecting each output to the segments of a 7 segment display. When the shift register pulls them high, the segments get brighter, but when it (should try to) pull them low, they don't turn off or get dimmer. They do turn off when I use two resistors though. But there's a problem there - I'm supplying it 3.3 V, so the single pull-up resistor (to a 3.3 V source) should only be pulling 1 mA, which is less than the "drive output" on the datasheet, so the shift register should be able to pull it low. Am I misunderstanding the datasheet or is something else going on here?

^{simulate this circuit – Schematic created using CircuitLab}

I understand that "drive output" on this datasheet means that it's the maximum current the IC can source/sink - i.e. if there is something pulling one of its outputs high at a current higher than 6mA, it cant pull the output low. This is, at least, what seems to be happening. If i put a 3.3kohm pull-up resistor on an output (to make it default to high when OE is high), the shift register cant seem to pull it low when OE is low. If I put a second resistor to get 6.6kohm, it can pull the output low. I'm measuring that it can't pull the resistor low by connecting each output to the segments of a 7 segment display. When the shift register pulls them high, the segments get brighter, but when it (should try to) pull them low, they dont turn off or get dimmer. They do turn off when I use two resistors though. But theres a problem there - I'm supplying it 3.3v, so the single pull-up resistor (to a 3.3v source) should only be pulling 1mA, which is less than the "drive output" on the datasheet, so the shift register should be able to pull it low. Am I misunderstanding the datasheet or is something else going on here?

I understand that "drive output" on this datasheet means that it's the maximum current the IC can source/sink - i.e. if there is something pulling one of its outputs high at a current higher than 6mA, it cant pull the output low. This is, at least, what seems to be happening. If i put a 3.3kohm pull-up resistor on an output (to make it default to high when OE is high), the shift register cant seem to pull it low when OE is low. If I put a second resistor to get 6.6kohm, it can pull the output low. I'm measuring that it can't pull the resistor low by connecting each output to the segments of a 7 segment display. When the shift register pulls them high, the segments get brighter, but when it (should try to) pull them low, they dont turn off or get dimmer. They do turn off when I use two resistors though. But theres a problem there - I'm supplying it 3.3v, so the single pull-up resistor (to a 3.3v source) should only be pulling 1mA, which is less than the "drive output" on the datasheet, so the shift register should be able to pull it low. Am I misunderstanding the datasheet or is something else going on here?

^{simulate this circuit – Schematic created using CircuitLab}

I understand that "drive output" on this datasheet means that it's the maximum current the IC can source/sink - i.e. if there is something pulling one of its outputs high at a current higher than 6mA, it cant pull the output low. This is, at least, what seems to be happening. If i put a 3.3kohm pull-up resistor on an output (to make it default to high when OE is high), the shift register cant seem to pull it low when OE is low. If I put a second resistor to get 6.6kohm, it can pull the output low. But theres a problem there - I'm supplying it 3.3v, so the single pull-up resistor (to a 3.3v source) should only be pulling 1mA, which is less than the "drive output" on the datasheet, so the shift register should be able to pull it low. Am I misunderstanding the datasheet or is something else going on here?

I understand that "drive output" on this datasheet means that it's the maximum current the IC can source/sink - i.e. if there is something pulling one of its outputs high at a current higher than 6mA, it cant pull the output low. This is, at least, what seems to be happening. If i put a 3.3kohm pull-up resistor on an output (to make it default to high when OE is high), the shift register cant seem to pull it low when OE is low. If I put a second resistor to get 6.6kohm, it can pull the output low. I'm measuring that it can't pull the resistor low by connecting each output to the segments of a 7 segment display. When the shift register pulls them high, the segments get brighter, but when it (should try to) pull them low, they dont turn off or get dimmer. They do turn off when I use two resistors though. But theres a problem there - I'm supplying it 3.3v, so the single pull-up resistor (to a 3.3v source) should only be pulling 1mA, which is less than the "drive output" on the datasheet, so the shift register should be able to pull it low. Am I misunderstanding the datasheet or is something else going on here?