25
votes
Accepted
What is ORing and why is it named ORing?
OR is a logical function - the output is high when either input is high.
ORing is simply a way of saying perform the logical OR of a set of signals.
In the context of power supplies, when ORing is ...
- 68.7k
13
votes
Accepted
Why include a small resistance between op-amp stages
The OPA633 has a peak in its frequency response at about 200 MHz of nearly 5 dB when the signal source impedance is 50 ohm. If the source impedance is about 300 ohm that peak is about 1 dB. If you ...
- 467k
10
votes
Accepted
Symmetric vs Asymmetric PWM
My question : According to ti's note http://www.ti.com/lit/an/spra278/spra278.pdf [page 10] symmetric PWM generates less harmonics ...
It depends on what other assumptions are being made, and there ...
- 171k
10
votes
Accepted
Best way to drive multiple LED strips at distinct times with one LED driver
Your boost LED driver circuit has high side current sensing, its output is ground referenced, so you can switch your LEDs with low side MOSFETs, which is convenient.
All you have to do is duplicate Q2 ...
- 80.3k
9
votes
Accepted
What are the purpose of the extra diodes in this peak detector circuit (LM1815)?
The actual (but probably still a bit simplified) circuit has no diodes, but a Darlington-ish pair Q23 and Q24 and the other lone "diode" is Q20, Q21 and dual collector transistor Q22.
The ...
8
votes
Choose a microcontroller
Unless you are targeting a specific feature, nearly all microcontrollers are the same.
How you choose can be up to you, but these are some of the things I look for when I am selecting a device or ...
- 12k
8
votes
What's importance of finite state machines (FSM) with respect to embedded systems implementation?
A FSM is a structured method of constructing a sequential machine. The machine can only exist in a fixed number of discrete states - ie ‘finite state’.
FSMs can be formally proven for correctness.
...
- 6,513
8
votes
Accepted
Low-side gate driver consistently shorts VDD to GND upon circuit power-up
You're simply operating the gate driver way outside of its absolute maximum ratings.
According to the datasheet, the driver can drive up to 4.5A pulses for at most 0.5µs. It can only drive 0.2A ...
- 20.1k
7
votes
Accepted
Choose a microcontroller
Should I choose TI, Microchip, Arm?
ARM doesn't make any actual chips. They just license their design to chipmakers. Microchip (Atmel) and TI (among others) both make chips based on ARM architecture.
...
- 132k
7
votes
DP83848 + STM32 & Failed EMC (massive spikes of 25MHz crystal harmonics)
Assuming L2 is the ground plane, the honking great opening in it between the processor and the ethernet chip gets my vote for proximate cause. I think the series resistors are a side issue that just ...
- 17.6k
7
votes
Accepted
What is the meaning of the "E" in the part number of Texas Instrument's CD4000 series?
You're looking at a catalog that only cares about the ceramic versions, so it only lists the suffixes for the ceramic versions.
Looking at a Harris (pre-TI) datasheet because it's a nice easy read:
...
- 7,948
7
votes
Accepted
What is the difference between SN74HCxxN and SN74HCxxAN parts?
TI's [FAQ] What is the difference between the SN74HCxx and the SN74HCxxA? says:
Some of these parts were translated into Japanese and renamed to SN74HCxxA. They have their own datasheets with ...
- 19.7k
6
votes
Frequency response of dual vs single op amp: OPA2890 vs OPA890
Does this make any sense?
Yes it does, from what I've seen they manufactures can use different silicon sometimes for a dual vs a single or quad part. But without actually seeing the die layout there ...
- 87.1k
6
votes
Accepted
Audio Conversion With ADS1243
You can't. The datasheet is surprisingly vague on this point, but this is a low-speed ADC, intended for instrumentation applications. The analog bandwidth is just a few tens of Hz at most.
- 176k
6
votes
Audio Conversion With ADS1243
You don't.
The ADS1243 datasheet gives an analog bandwidth of maximum 14.6 Hz.
That's well below what anyone would normally call audio.
The ADS1243 is intended for high resolution sampling of slow ...
- 73.1k
6
votes
Accepted
Can I "sum" internal ADC channels to achieve extra bits resolution?
If you dither the signal and average more than 256 samples you can get some apparent resolution (not accuracy) increase, but frankly you’d be far better off ignoring the on-chip ADC and using an ...
6
votes
How are embedded C compilers different from C compilers used for desktop applications?
If we look at gcc that is targetted to the ARM platform ( as there are builds for ‘bare metal’ and Linux) the main differences is the runtime environment. In the bare metal build (arm-none-eabi) the C ...
- 6,513
6
votes
What does (DW) mean in the TI equivalent of SOIC (16) package?
In general these are references to manufacturer-specific package designs. They may or may be identical or similar enough to those other manufacturers use, you have to check yourself if you are ...
5
votes
Accepted
24V to 5V converter using a LM3489
I verified all my circuit but nothing is wrong
I beg to differ.....
Using a 0.1 uF capacitor across the feedback resistor is asking for trouble. The data sheet says that it should be 100 pF i.e. ...
- 467k
5
votes
Accepted
Frequency response of dual vs single op amp: OPA2890 vs OPA890
It looks like there is an actual difference between the OPA890 and the OPA2890. For example, the parametric table on the OPA890's description page shows that the OPA890 has a slightly higher GBW (260 ...
Null♦
- 7,633
5
votes
Accepted
DP83848 + STM32 & Failed EMC (massive spikes of 25MHz crystal harmonics)
(A) The internal rails (VDD and Ground) of microprocessors will ring at each clock edge transition; this frequency will be in range of 100 to 200 MHz, because of the total inductances (1nH?) and the ...
- 34.6k
5
votes
Accepted
Compiler optimization prevents code from running
Prior to learning to implement this using timers/interrupts I would recommend not rolling your own delayMs function. There is a SysCtlDelay(int count) function ...
- 547
5
votes
Boost converter TPS61040 output voltage higher than expected
How is this possible?
You have the feedback potential divider in the wrong place. It should be like this: -
I've circled the diode to show that it has moved. You also need an output capacitor.
- 467k
5
votes
Accepted
5
votes
What does (DW) mean in the TI equivalent of SOIC (16) package?
The "Device Information" box on the first page of the datasheet show that the DW package is 10.3 x 7.5 mm, whiile the DWW package is 10.3 x 14 mm.
Section 13 of the datasheet has dimensioned ...
- 60.2k
5
votes
Accepted
What does (DW) mean in the TI equivalent of SOIC (16) package?
Chapter 1 of the data sheet gives us a clue:
SOIC-16 Wide Body (DW) and Extra-Wide Body
(DWW) Package Options
So the "W" stands for "wide", and "WW" for "extra ...
- 3,406
5
votes
Accepted
Is TI lying or over selling their solar charging ICs?
Is TI lying ...
Almost definately not.
... or over selling their solar charging ICs?
Not likely either, though it could be an honest mistake - feel free to contact TI for clarification on this ...
- 2,438
4
votes
Accepted
Smart Card (SIM) clocking requirements
First, everything is specified in ISO7816-3. You should really read it (I won't provide any links because the standard is not free, but you can still easily find it on the web). Now, regarding your ...
- 16.1k
4
votes
Accepted
Proper use of CD4504BE Level Shifter IC for SPI
Are these connections correct? If not, how should these be connected?
Yes. Except that SELECT pin shall be connected to Ground.
I would like to shift this 3.3V signal up to 5V. Is this possible
...
- 9,341
4
votes
Accepted
Interfacing 20x4 character LCD with TI TM4C1294 generates some random characters
Your function LCD_SendCmd contains the following line:
GPIO_PORTL_DATA_R |= 0x00;
Which does nothing. What it should do is set bit 0 to zero to access the ...
- 5,865
Only top scored, non community-wiki answers of a minimum length are eligible