LNK302/304-306
TOPOLOGY BASIC CIRCUIT SCHEMATIC
KEY FEATURES
High-Side
Buck –
Direct
1. Output referenced to input
2. Positive output (VO) with respect to -VIN
3. Step down – VO < VIN
FB
BP
S
Feedback
4. Low cost direct feedback (±10% typ.)
D
+
+
LinkSwitch-TN
VIN
VO
PI-3751-121003
High-Side
Buck –
Optocoupler
Feedback
1. Output referenced to input
2. Positive output (VO) with respect to -VIN
3. Step down – VO < VIN
FB
BP
S
D
+
+
4. Optocoupler feedback
LinkSwitch-TN
- Accuracy only limited by reference
choice
VIN
VO
- Low cost non-safety rated opto
- No pre-load required
5. Minimum no-load consumption
PI-3752-121003
Low-Side
Buck –
+
+
Optocoupler
Feedback
LinkSwitch-TN
VIN
VO
1. Output referenced to input
2. Negative output (VO) with respect to +VIN
3. Step down – VO < VIN
BP
FB
D
S
PI-3753-111903
4. Optocoupler feedback
- Accuracy only limited by reference
choice
Low-Side
Buck –
Constant
Current LED
Driver
+
IO
LinkSwitch-TN
- Low cost non-safety rated opto
- No pre-load required
- Ideal for driving LEDs
VF
VIN
+
BP
FB
D
S
PI-3754-112103
VF
IO
R =
High-Side
Buck Boost –
Direct
FB
BP
S
Feedback
D
+
LinkSwitch-TN
1. Output referenced to input
VIN
VO
+
2. Negative output (VO) with respect to +VIN
3. Step up/down – VO > VIN orVO < VIN
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
PI-3755-121003
High-Side
Buck Boost –
Constant
Current LED
Driver
2 V
300 Ω
RSENSE
=
IO
2 kΩ
RSENSE
FB
BP
IO
S
D
+
LinkSwitch-TN
VIN
10 μF
50 V
100 nF
PI-3779-120803
Table 2. Common Circuit Configurations Using LinkSwitch-TN. (continued on next page)
26-6
Rev. I 11/08
POWERINT [ Power Integrations ]
