Table I.
Functionality of the integrated chip (IC) components in the wearable controller (In the order of decreasing power consumption).
| Component | IC model, company | Key IC features | Current, mA | Power cons., mW |
|---|---|---|---|---|
| Bluetooth communication | F2M03GLA, Free2move | Bluetooth V.2.0+EDR, UART | 44/22* | 145/73* |
| Rx from Bluetooth, PWG & EPG | PIC18F4620, Microchip Tech. | 3K RAM, 1K EEPROM, UART, SPI | 21/10* | 105/50* |
| Tx to Bluetooth | PIC18F2620, Microchip Tech. | 3K RAM, 1K EEPROM, UART, SPI | 21/10* | 105/50* |
| 16-ch. V-to-I converter (Howland pump) | TLV2741 × 8, Texas Instruments | R-R output, high GBW & SR | 3.2 per ch. | 19 per ch. |
| D/A converter | TLV5626, Texas Instruments | 8 bit, 0.28/sec, SPI | 3.7 | 18.5 |
| Amplifier & voltage shifter | TLV271 × 2, Texas Instruments | R-R output, high GBW & SR | 1.1 | 17.6 |
| A/D converter | ADS7886, Texas Instruments | 12 bit, 1 Ms/sec, SPI | 1.5 | 7.5 |
| 16-ch. analog switch for electrode grounding | PS393 × 4, Pericom | Low leakage current (<2 pA) | 0.004 | 0.064 |
| 16-ch. analog switch for stimulation selection | PS393 x 4, Pericom | Low leakage current (<2 pA) | 0.004 | 0.064 |
| 16:1 analog MUX for recording selection | MAX396, Maxim | Low leakage current (30 pA) | 0.001 | 0.016 |
| Total | 96/52* | 418/236* |
In the Current and Power consumption columns, the second value, marked by asterisk (*), indicates an idle state. Abbreviations: A/D—analog-to-digital, consump.—consumption, D/A—digital-to-analog, EDR—Enhanced Data Rate, GBW—gain bandwidth product, Ms—megasamples; PWG & EPG—pulse waveform generator and electrode pattern generator, SPI—serial peripheral interface bus, SR—slew rate, R-R—rail-to-rail, Tx—transmission of data, UART—universal asynchronous receiver/transmitter bus, V-to-I—voltage-to-current