Programmable read-only memory
One Time Programmable (OTP ) is a term of the electronics. Under an OTP block is defined as a programmable electronic component, which includes a non-volatile memory (PROM). This memory can, however, describe only once. Depending on the design of the device may be additionally required a programmer. Meanwhile, there are a multiplicity of components, which are also produced in the OTP technology.
OTP technology can basically be implemented as a fuse technology, or as an anti-fuse technology. In preparing the OTP devices through the semiconductor manufacturers all joints are open, for example, in the antifuse technology, only by programming the relevant connection points are connected.
However, there are also "false " OTP memory, which are implemented as so-called " OTP area" in some flash memories. These memory areas are usually from normal flash cells, which are secured by additional logic to change.
Areas of application
OTP technology can be used, for example in the subsequent components.
- PLA (Programmable Logic Array) - A rewritable version of this are GALs
- FPGAs ( Field Programmable Gate Array) - also available reprogrammable
Individual OTP areas also exist in certain devices, such as flash memories, smart cards and microcontrollers, which serve to store serial numbers or other identification data unalterable. An example of this is the IMEI of most modern mobile phones.
The advantage of the OTP technology is that the circuit function of the programmed devices (including inadvertently not ) can not be changed. Compared to devices with on-screen programming can react quickly to a change of the data content in the module production through the use of OTP devices.
The OTPs have the practical circuit design but crucial disadvantages that must be considered in the circuit design. Once programmed, and once installed on a module, the logic function of this device can be changed only by an exchange of the device ( from the circuit board and soldering the new component on the circuit board = desoldering the old component ). A function expansion, as is customary, for example, by a software update or a change in the logic circuit function in other programmable logic devices today is generally not possible with the OTP devices.
Furthermore, the scope of an error in the function or when programming the OTP devices must not be underestimated. The larger the circuit function, the greater is the risk that the function is an error which can not be found even with the development of the test. In extreme cases, may have an expansion of the device to the end customer and a change by the manufacturer result in a malfunction.
- Semiconductor memory technology
- Programmable Logic