ADT7350
APPLICATION INFORMATION
Output Voltage Setting
Enable resistor Setting (R3)
Step 1) Determine R1 value
The current of feedback resistors is
Above figure is simplified input stage of ADT7350.
I
FB
_
RES
½
V
OUT
R
1
R
2
V
EN
½
R
INT
1
R
INT
2
V
IN
R
INT
1
R
INT
2
R
3
R_int1=1KΩ , R_Int2=1MΩ
In order to get the good sensitivity, increase
this current in spite of such amount of
current consumption.
(Refer to following table for reasonable start)
Step 2) Determine R2 value the basis of
following equation.
Example) VIN=12V
1) R3=1MΩ
1
K
1
M
V
EN
½
V
IN
5.8
V
1
K
1
M
1
M
The zener diode clips this voltage into 5.8V
2) R3=2MΩ
V
EN
½
1
K
1
M
V
IN
½
4
V
1
K
1
M
2
M
1
K
1
M
V
IN
½
2
V
1
K
1
M
5
M
R
2
½
R
1
V
OUT
1
V
REF
@V
REF
=810mV
The voltage of feedback should be equal to internal
reference voltage in well-designed negative
feedback loop.
VOUT (V)
1.2
1.8
2.5
3.3
5
7
10
15
R1(KΩ)
80.6
80.6
49.9
49.9
49.9
49.9
80.6
80.6
R2 (KΩ)
160
64.9
23.7
16.2
9.53
6.53
6.98
4.53
L(µH)
2.2
2.2
4.7
4.7
4.7
4.7
10
10
3) R3=5MΩ
V
EN
½
* This specifications are subject to be changed without notice
Aug 21. 2012 / Rev. 0.2
9/10
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