Datasheet
6
LNK302/304-306
G
3/05
Table 2. Common Circuit Configurations Using LinkSwitch-TN. (continued on next page)
TOPOLOGY BASIC CIRCUIT SCHEMATIC KEY FEATURES
High-Side
Buck –
Direct
Feedback
1. Output referenced to input
2. Positive output (V
O
) with respect to -V
IN
3. Step down – V
O
< V
IN
4. Low cost direct feedback (±10% typ.)
High-Side
Buck –
Optocoupler
Feedback
1. Output referenced to input
2. Positive output (V
O
) with respect to -V
IN
3. Step down – V
O
< V
IN
4. Optocoupler feedback
- Accuracy only limited by reference
choice
- Low cost non-safety rated opto
- No pre-load required
5. Minimum no-load consumption
Low-Side
Buck –
Optocoupler
Feedback
1. Output referenced to input
2. Negative output (V
O
) with respect to +V
IN
3. Step down – V
O
< V
IN
4. Optocoupler feedback
- Accuracy only limited by reference
choice
- Low cost non-safety rated opto
- No pre-load required
- Ideal for driving LEDs
Low-Side
Buck –
Constant
Current LED
Driver
High-Side
Buck Boost –
Direct
Feedback
1. Output referenced to input
2. Negative output (V
O
) with respect to +V
IN
3. Step up/down – V
O
> V
IN
or
V
O
< V
IN
4. Low cost direct feedback (±10% typ.)
5. Fail-safe – output is not subjected to input
voltage if the internal MOSFET fails
6. Ideal for driving LEDs – better accuracy
and temperature stability than Low-side
Buck constant current LED driver
High-Side
Buck Boost –
Constant
Current LED
Driver
V
O
V
IN
PI-3751-121003
+
+
FB
BP
S
D
LinkSwitch-TN
LinkSwitch-TN
PI-3752-121003
+
+
BP
FB
D
S
V
O
V
IN
LinkSwitch-TN
PI-3753-111903
+ +
BP
FB
D
S
V
O
V
IN
LinkSwitch-TN
PI-3754-112103
+
+
BP
FB
D
S
V
IN
I
O
R =
V
F
V
F
I
O
V
O
V
IN
PI-3755-121003
+
+
FB
BP
S
D
LinkSwitch-TN
R
SENSE
=
R
SENSE
300 Ω
2 kΩ
2 V
I
O
I
O
100 nF
10 µF
50 V
V
IN
PI-3779-120803
+
FB
BP
S
D
LinkSwitch-TN