What are the MAX1617 high and low level currents?

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Accepted Answer

In the specification table of remote-diode source current, there are 2 conditions, one is high level and the other one is low level. Waht is the definition of high/low level current?

The expression of temperature using a remote BJT can be written as 
 
T = (q x VBE)/(ln(Ic/Is)) 
 
The above expression shows that the base-emitter voltage of a BJT is directly proportional to the absolute temperature. Thus, setting a known collector current and measuring the VBE gives us the temperature. However, the Is (saturation current) of a transistor varies from one transistor to another because of process differences and can introduce errors in the temperature readings. Therefore, to avoid this dependency, a two current method is used. In this method a device (like the MAX1617) that is capable of supplying two values of currents in the collector of BJT with known current ratio K between them, is used. The main aim is to make the temperature measurement independent of the variation in the saturation current as follows: 
 
VBE = (K x T/q)ln(Ic/Is) 
 
When the current from source 1 flows the VBE can be calculated as follows: 
 
VBE1=(K x T/q)ln(Ic1/Is1) 
 
Similarly when the current from source 2 flows the VBE can be calculated as follows: 
 
VBE2=(K x T/q)ln(Ic2/Is2) 
 
Subtracting the second equation from the first 
 
dVBE=(K x T/q)ln(Ic1/Ic2) 
 
dVBE=(K x T/q)ln(K) 
 
In this way the variation in base-emitter voltage depends on the known current ratio K. In the MAX1617 the value of K is 10 
 
Low-level is the second current source (min 8, typ 10, max 12). 
High-level is the first current source (min 80, typ 100, max 120).

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MAX1617: FAQ