Datasheet ZXRE160 (Diodes) - 10

A Product Line of Diodes Incorporated ZXRE160 Application Information
(cont.) ⎛ 1 R ⎞ V = V ⎜1+ ⎟ OUT REF ⎝ R2 ⎠
T
≥ + OUT V 0.2V BE V
UC
− IN V OUT V 3 R = R I 3
Figure 8. 1V Current-Boosted Shunt Regulator NEW PROD Design guide
1. Determine IOUT and choose a suitable transistor taking power dissipation into consideration. 2. Determine I I B from OUT(max) I = B (h + ) 1 FE(min) 3. Determine IR3 from R I = 3 I (max) OUT V − V 4. Determine R3 from IN OUT 3 R = R I 3 5. It is best to let the ZXRE160 supply as much current as it can before bringing Q1 into conduction. Not only does this minimize the strain on Q1, it also guarantees the most stable operation. Choose a nominal value between 10mA and <15mA for this current, IR4. V Calculate R4 from BE R4 = R I 4 VOUT goes low and LED is lit when monitored supply ⎛ 1 R ⎞ > ⎜1+ ⎟ REF V M V ⎝ R2 ⎠ − ( + 0.2) IN V F V 3 R = 3 R I mA 15 ≥ ≤ ) MAX ( F I 3 R I VF and IF are forward voltage drop and current of LED1.
Figure 9. 1.15V Over-Voltage Indicator
ZXRE160 10 of 15 June 2012 Document number: DS35688 Rev. 2 - 2
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