Reading Datasheets
Contents
Background information
The key to reading datasheets is to know what you're looking for, since they contain all the data on the device you might need across multiple disciplines.
This page aims to tell you what you need to look for depending on what questions you may have please see locate datasheets and schematics for research methods
Data sheets are often broken up in to multiple parts which an overview at the top the datasheet that provides the key information such as features of the device, application of it, and a brief description of the device's purpose
Pin configuration
This segment tends to present a pinout diagram listing the names and numbers of the pins on the corresponding diagram pin alongside with the chip's physical dimensions alongside a table which lists the purposes of each pin alongside the pin name.
Pin Diagram
+---------------------+
| QB 1 16 VCC|
| QC 2 15 QA |
| QD 3 14 SER|
| QE 4 13 OE |
| QF 5 12 RCLK|
| QG 6 11 SRCLK|
| QH 7 10 SRCLR|
| GND 8 9 QH' |
+---------------------+
Specifications
This section lists the minimum maximum values a chip can handle, as well as the units these measurements are measured in. A separate table also lists the recommended operating values for a chip in the same fashion as the section mentioned above, it also lists the amount of time it takes for a chip to react to changes.
Truth/function tables and Timing Diagrams
Truth/function tables
Truth tables lay out all possible combinations of inputs and the functions these create (such as pulling the two pins high starts the function, clearing the shift register)
The type of signal is denoted though symbols such as H dictates a High input/output an L dictates a Low input/output and an X dictates a "chips don't care"
meaning that the type of signal does not have an effect on the outcome.
A similar system based on arrows is used for high to low (falling edge)↓ signals and low to high (rising edge)↑ signals, which dictate the direction of the signal on its Y axis.
Function Table
| SER | SRCLK | SRCLR | RCLK | OE | Function |
|-----|-------|-------|------|----|------------------------|
| X | X | X | X | H | Outputs disabled |
| X | X | X | X | L | Outputs enabled |
| X | X | L | X | X | Shift register cleared |
| L | ↑ | H | X | X | First stage goes low |
| H | ↑ | H | X | X | First stage goes high |
| X | X | X | ↑ | X | Data stored |
Timing diagrams
Timing diagrams detail chip behaviour and how each line acts when certain actions are taken, while also listing the exact order of operations(OOP), timings and delays between each signal
which can be used to figure out how long certain signals must be stable in order to be considered valid inputs, which can then allow for you to communicate with the chip over the protocols in place.
Timing Diagram
SRCLK: ────┐┌────┐┌───
SER: ───────┐──────
RCLK: ──┐ ┌──┐ ┌───
SRCLR: ──────────────
OE: ───────┐──────
QA-QH': ─┐─┐───┐───┐──
Plots and graphs
These present the information above in a visual format which often is easier to understand or find how a chip operates when exposed to certain values such as extreme cold or prolonged high voltage
which can help to design around these problems to protect against the chip's weaknesses if it is going to be frequently exposed to these types of environment.
graph
Y-axis
^
| -----*
| ----* *
| ---* *
| -- * *
|- * *
|*_________*_________> X-axis
Step-by-step guide with images
Insert step-by-step walkthrough with images and summary text here
Flow chart of order of operations
Insert a flow chart of steps and actions for each task (create using diagram)
Troubleshooting/tips and tricks
Fixes to any common issues that were encountered or could be easily encountered
Related Topics
Topics such as desoldering to chip off or firmware dumping for disk PCB repairs
Further reading
External references in wiki references can just be cited through the keyword link
- Reference 1: understand technical datasheets
- Reference 2: Source details