Thermally_based_NiCad_charger

Published:2009/7/24 5:10:00 Author:Jessie | From:SeekIC

Figure 8－15 shows a simple thermally based charging circuit for NiCad batteries．Figure 8-16 shows the charge characteristics．Thermocouples sense both cell andambient temperature simultaneously. A1 provides the amplification necessary for microvolt-level thermocouple signals． The 10-kΩ trimpot is set to introduceenough input-off set so that the A1 output swmgs positive turning on thetransistor． Figure 8-17 shows a simple, lnexpenslve way to construct low-resistance shunts usmg a small length of wlre or a PC trace．The type and length of wire determines the shunt resistance (which can be altered to produce the desiredcharging characteristics). Figure 8-17 also shows resistance-versus-len gth characteristics for varlous wire sizes, as well as the details for both wlre and PC shunts．In both cases (PC or wire) the shunt should have separate connections for sensing (Kelvin style) SO that high current does not affect the readings.LINEARTECHNOLOGY， APPLICATION NOTE 37.P.4．



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