If the 317 and 337 swap places and the diodes reverse, Figure 3's circuit can work for negative current, too

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Other Materials from the Main Document

• Article «Cross connect complementary current sources to reduce self-heating error»
• Figure 1. How to control amps of I_OUT with mA of I_C using legacy voltage regulators as current regulators where I_OUT = (V_ADJ - I_CR_C)/R_S
• Figure 2. LM317 reference variation with junction temperature as seen in page 5 of LM317 datasheet
• Figure 3. Cross connection reduces self-heating error because shunt regulator U2 carries most of the current, getting relatively hot, while U1, whose V_REF is in control, stays relatively cool and accurate
• Figure 4. If the 317 and 337 swap places and the diodes reverse, Figure 3's circuit can work for negative current, too
• Figure 5. Boost current handling capacity with beefier diodes and more U2s
• Figure 6. Negative current source circuit incorporates means for compensating component tolerances, including those of U1 and Z1 references. Note R_S = 1.1 Ω and should be rated for more than 1 W