LNK302/304-306
Topology
High-Side
Basic Circuit Schematic
Key Features
±. Output referenced to input
Buck –
Direct
2. Positive output (VO) with respect to -VIN
3. Step down – VO < VIN
Feedback
4. Low cost direct feedback (±±05 typ.)
1. Requires an output load to maintain regulation
FB
BP
S
D
+
+
LinkSwitch-TN
VIN
VO
PI-3751-041509
High-Side
Buck –
Optocoupler
Feedback
±. Output referenced to input
2. Positive output (VO) with respect to -VIN
3. Step down – VO < VIN
FB
BP
S
4. Optocoupler feedback
D
+
+
- Accuracy only limited by reference choice
- Low cost non-safety rated optocoupler
- No pre-load required
LinkSwitch-TN
VIN
VO
1. Minimum no-load consumption
PI-3752-041509
Low-Side
Buck –
+
+
Optocoupler
Feedback
LinkSwitch-TN
VIN
VO
BP
FB
±. Output referenced to input
2. Negative output (VO) with respect to +VIN
3. Step down – VO < VIN
D
S
PI-3753-041509
Low-Side
Buck –
Constant
Current LED
Driver
4. Optocoupler feedback
+
IO
- Accuracy only limited by reference choice
- Low cost non-safety rated optocoupler
- No pre-load required
LinkSwitch-TN
VF
VIN
+
- Ideal for driving LEDs
BP
FB
D
S
PI-3754-041509
VF
IO
R =
High-Side
Buck-Boost –
Direct
FB
BP
S
Feedback
D
+
±. Output referenced to input
LinkSwitch-TN
VIN
VO
+
2. Negative output (VO) with respect to +VIN
3. Step up/down – VO > VIN orVO < VIN
4. Low cost direct feedback (±±05 typ.)
1. Fail-safe – output is not subjected to input
voltage if the internal power MOSFET fails
6. Ideal for driving LEDs – better accuracy and
temperature stability than Low-side Buck
constant current LED driver
PI-3755-041509
High-Side
Buck-Boost –
Constant
Current LED
Driver
2 V
300 Ω
RSENSE
=
IO
2 kΩ
RSENSE
FB
BP
S
IO
D
+
LinkSwitch-TN
VIN
7. Requires an output load to maintain regulation
10 µF
100 nF
50 V
PI-3779-041509
Table 2.
Common Circuit Configurations Using LinkSwitch-TN. (continued on next page)
6
Rev. J 06/13
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