Application information – Diodes ZXRE060 User Manual
Page 8
ZXRE060
0.6V ADJUSTABLE PRECISION SHUNT REGULATOR
ZXRE060
Document number: DS33611 Rev. 6 - 2
8 of 12
March 2011
© Diodes Incorporated
A Product Line of
Diodes Incorporated
Application Information
(Continued)
Figure 7. 1V Current-boosted shunt regulator
⎟
⎠
⎞
⎜
⎝
⎛ +
=
2
R
1
R
1
REF
V
OUT
V
(
BE
V
V
2
.
0
OUT
V
+
≥
)
3
R
I
OUT
V
IN
V
3
R
−
=
Design guides
1. Determine
I
OUT
and choose a suitable transistor taking power dissipation into consideration.
2. Determine
I
B
from
)
1
(min)
FE
h
(
(max)
OUT
I
B
I
+
=
3. Determine
I
R3
from
(max)
OUT
I
3
R
I
=
4. Determine R3 from
3
R
I
OUT
V
IN
V
3
R
−
=
5. It is best to let the ZXRE060 supply as much current as it can before bringing Q1 into conduction. Not
only does this minimise the strain on Q1, it also guarantees the most stable operation. Choose a nominal
value between 10mA and <15mA for this current, I
R4
.
6. Calculate R4 from
4
R
I
BE
V
4
R
=
Figure 8. 1.15V over-voltage indicator
V
OUT
goes low and LED is lit when monitored supply
⎟
⎠
⎞
⎜
⎝
⎛ +
>
2
R
1
R
1
REF
V
M
V
3
R
I
)
2
.
0
F
V
(
IN
V
3
R
+
−
=
)
MAX
(
F
I
3
R
I
mA
15
≤
≥
V
F
and I
F
are forward voltage drop and current of LED1.