Supertex (www.supertex.com), a developer of analog and mixed signal integrated circuits (ICs), has released a current sensing IC, the HV7800, for use in high-side current sensing topologies. One of the interesting features of this device is its wide input range of 8 Vdc to 450 Vdc. This enables the device to work with a variety of standard dc and offline ac power systems.
The wide input voltage range also allows the part to monitor current in telecom and base station applications, power management applications, and LCD TVs with LED backlights. For the latter application, the HV7800 is recommended for use in conjunction with Supertex’s LED driver IC, the HV9911.
High-side current sensing allows the ground in a circuit to be undisturbed when sensing input or load currents. Grounding system impedances in low-side current sensing often cause signal degradation or electromagnetic interference. Because the HV7800 is configured for use on the high side of a circuit, it avoids these sensing problems and provides a much easier sensing implementation. Yet another possible advantage of the topology is that it allows the load to maintain a direct connection to ground, which could be critical for certain types of load components, such as ICs with single-ended inputs and outputs.
According to Gary Giust, Technical Marketing Manager for Supertex, the input sensing voltage is set to 0.5 V, which is within the range of similar products on the market. However, this product was created using Supertex’s high-voltage process technology, which enables its wide input voltage range. The part also has the same robust internal surge and ESD protection circuits found in other Supertex products implemented with the same high-voltage process.
The HV7800 is available in a 5-pin SOT23 package. The part is “Green” and RoHS compliant. Samples are available from stock, and pricing is $0.56 each in 1000-unit quantities.