The FHR1200 offers greatly expanded specifications versus that of the LM431. This includes: much wider operating temperature and voltage range, and the ability to directly drive a power supply controller unlike the LM431. Finally, the FHR1200 has much lower operating current for those applications where low Standby Power is important.
The FHR1200 can operate down to currents as low as 10uA. This can result in significant power savings when compared to the LM431. The following figure illustrates this.
Typical 24 V Output Regulator - Industry Standard LM431
Assumptions: (24 V Output FHR1200)
Another example of the power savings that can be realized with the FHR1200 is the following comparison of an LM431 output regulated supply versus a FHR1200 output regulated supply.
192 W LCD TV Schematic of FSFR2100 Evaluation Board (LLC Resonant Converter)
The FHR1200 is very flexible. A simple discrete "Brown-Out" Regulator can be made using the FHR1200. The output regulator is also a FHR1200.
As previously stated, the FHR1200 is very flexible so can be adapted to many different applications. The following illustration shows two ways the FHR1200 may be used to replace discrete components to regulate the input side of a LED offline power supply. On the left side, CV regulation is achieved two ways. First, a zener diode and BJT are used to sense the controller Vcc voltage, and to drive the feedback terminal of a controller chip. The Vcc voltage is used to represent the overall power supply output voltage. A problem with this is that regulating from the Vcc voltage requires an accurate voltage regulator. Using the FHR1200 rather than discrete components can significantly improve the regulator accuracy. Second, the Vcc voltage is used to feedback the error in the output voltage by driving the current limit pin on the controller. Once again this requires an accurate zener. Replacing the discrete zener with a programmable zener made up of the FHR1200 and two resistors can significantly improve accuracy.