LNK302/304-306
TOPOLOGY
High-Side
Buck –
Direct
Feedback
+
V
IN
BASIC CIRCUIT SCHEMATIC
KEY FEATURES
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.)
+
V
O
FB
D
BP
S
LinkSwitch-TN
PI-3751-121003
High-Side
Buck –
Optocoupler
Feedback
FB
BP
S
+
V
IN
D
+
V
O
LinkSwitch-TN
PI-3752-121003
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
+
LinkSwitch-TN
V
IN
+
V
O
BP
S
FB
D
PI-3753-111903
Low-Side
Buck –
Constant
Current LED
Driver
+
LinkSwitch-TN
V
IN
I
O
V
F
+
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
BP
S
FB
D
R=
V
F
PI-3754-112103
I
O
High-Side
Buck Boost –
Direct
Feedback
+
V
IN
FB
D
BP
S
LinkSwitch-TN
V
O
PI-3755-121003
High-Side
Buck Boost –
Constant
Current LED
Driver
300
Ω
2 kΩ
FB
BP
S
R
SENSE
=
2V
I
O
I
O
R
SENSE
+
V
IN
D
LinkSwitch-TN
10
μF
50 V
100 nF
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
PI-3779-120803
Table 2. Common Circuit Configurations Using LinkSwitch-TN. (continued on next page)
2-6
6
Rev. H 12/06
+
FERYSTER [ FERYSTER INDUCTIVE COMPONENTS MANUFACTURER ]
