ECG input amplifiers must withstand high-voltage pulses for cardiac resuscitation. These pulses can easily damage the sensitive electronic circuitry which captures the millivolt level heart signals. Preventing this damage has required a three-layer, multi-component approach combining a per-channel gas-discharge tube (GDT) and/or transient-voltage suppression (TVS) device, as well as ESD-protection diodes. Further, leakage current (a critical parameter) is relatively high, at about 1-2 nA.
Maxim's four-channel MAX30034 defibrillation protection device uses an innovative topology from an advanced semiconductor process to absorb and harmlessly redirect these high-energy pulses away from sensitive circuitry. This small and robust device needs only two external pairs of resistors for each channel to provide design simplicity, smaller overall size, and lower leakage current. The MAX30034 replaces the primary-level GDTs and/or TVSs, as well as secondary-level ESD diodes which are the conventional solutions for mandated circuit protection. The device can withstand over 100,000 defibrillation pulses without failure and still maintain a leakage current under 10 pA (100x less than GDT/TVS-based approaches).
A single, tiny IC, and two external resistor pairs per channel are all that is needed; leakage current is 100x less than GDT/TVS-based approaches even after 100,000 5 kV pulses; and the device ecomes in a 3 x 5 mm µMAX packagefor $3.40 (1000). An evaluation kit is available for $25: MAX30034EVKIT#
Maxim Integrated; http://bit.ly/MAX30034