Compensation Current Resistor (R
I
) Calculation
Temperature-Compensated Solar Battery Charger
The Value of R
I
(LM34)
R
I
=
Sensor (LM34) Output Voltage (mV/°F) [10]*
÷
Required Correction Voltage (mV/°C) [12]
x
C to F Conversion [9/5]
x
LM317 ADJ Node Resistance to Ground [R
adj
]**
*From LM34 data sheet. **From Table 1, or calculate R
adj
= 1/(1/2610 + 1/R1)
So:
From Table 1, R
adj
= 2556.4Ω
R
I
= 10/12 x 9/5 x 2556.4 = 3834.6
Install nearest 1%. 3830 Ω would be a typical value for R
I
.
The Value of R
I
(LM35)
R
I
=
Sensor (LM35) Output Voltage (mV/°C) [10]*
÷
Required Correction Voltage (mV/°C) [12]
x
LM317 ADJ Node Resistance to Ground [R
adj
]**
*From LM35 data sheet. **From Table 1, or calculate R
adj
= 1/(1/2610 + 1/R1).
So:
From Table 1, R
adj
= 2517.5Ω
R
I
= 10/12 x 2517.5 = 2097.9
Install nearest 1%. 2100 Ω would be a typical value for R
I
.
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