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11A34: Difference between revisions
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The 11A34 uses the same firmware as the [[11A32]]. | The 11A34 uses the same firmware as the [[11A32]]. | ||
Each of the four channels has its own M377 amplifier. | |||
The display outputs of the four amplifiers are combined in parallel and drive the 50 Ω impedance of the mainframe. | |||
The same is true of the trigger outputs of the four amplifiers. | |||
The version of the M377 used in the 11A34 has 200 Ω output impedance so that four of them in parallel create an equivalent source impedance of 50 Ω. | |||
The amplifiers can be connected in parallel because regardless of whether the amplifier's output is enabled: | |||
* each amplifier's output has a source impedance of 200 Ω so the two amplifiers in parallel match the 50 Ω spec of the [[11000 Series plug-in interface]]. | |||
* each amplifier's nominal common-mode output voltage is zero | |||
* each amplifier's nominal differential output voltage is zero | |||
See the block diagram below. | |||
{{BeginSpecs}} | {{BeginSpecs}} | ||
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Each channel's attenuator module contains an [[M474]] buffer amplifier. | Each channel's attenuator module contains an [[M474]] buffer amplifier. | ||
Each of the attenuator modules drives an [[M377]] amplifier IC. | Each of the attenuator modules drives an [[M377]] amplifier IC. | ||
The 11A32 and 11A34 were originally intended to use Intel 8052 microcontrollers. | |||
However, during development, the firmware swelled beyond that chip's 8192-byte maximum on-chip ROM size. | |||
[[Doug Haines]] found an alternate supplier of 8051-compatible chips (OKI Semiconductor) that offered a 16Kbyte on-chip ROM, | |||
and that's what the plug-ins wound up with. The finished code size wound up at about 14 KB. | |||
The 11A34 contains two [[ACVS]] sample and hold modules. | The 11A34 contains two [[ACVS]] sample and hold modules. | ||