Figure 9-1 shows a typical application circuit for the LMR436x0. This device
is designed to function over a wide range of external components and system
parameters. However, the internal compensation is optimized for a certain range of
external inductance and output capacitance. As a quick-start guide, Table 9-1 and Table 9-3 provide typical component
values for a range of the most common output voltages.
Table 9-1 Typical External Component
Values for Adjustable Output LMR43620
ƒSW (kHz)(1) |
VOUT (V) |
L (µH)(2) |
NOMINAL COUT (RATED CAPACITANCE) |
MINIMUM COUT (RATED
CAPACITANCE) |
RFBT (kΩ) |
RFBB (kΩ) |
CIN |
CBOOT |
CVCC |
CFF |
400 |
3.3 |
10 |
3 × 22 µF |
1 × 47 µF |
33.2 |
14.3 |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
22 pF |
1000 |
3.3 |
4.7 |
2 × 22 µF |
3 × 10 µF |
33.2 |
14.3 |
2.2 µF + 1 × 100
nF |
100 nF |
1 µF |
22 pF |
2200 |
3.3 |
2.2 |
2 × 22 µF |
1 × 22 µF |
33.2 |
14.3 |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
22 pF |
400 |
5 |
10 |
3 × 22 µF |
1 × 47 µF |
49.9 |
12.4 |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
22 pF |
1000 |
5 |
4.7 |
2 × 22 µF |
3 × 10 µF |
49.9 |
12.4 |
2.2 µF + 1 × 100
nF |
100 nF |
1 µF |
22 pF |
2200 |
5 |
2.2 |
2 × 22 µF |
1 × 22 µF |
49.9 |
12.4 |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
22 pF |
(1) The switching frequencies listed here can be achieved in a number of ways
depending on the device variant. For RT devices see
Section 8.3.3. For MODE/SYNC devices see
Section 8.3.2.
(2) Inductor values are calculated
based on typical VIN = 13.5 V.
Table 9-2 Typical External Component Values for Adjustable Output LMR43610
ƒSW (kHz)(1) |
VOUT (V) |
L (µH)(2) |
NOMINAL COUT (RATED CAPACITANCE) |
MINIMUM COUT (RATED
CAPACITANCE) |
RFBT (kΩ) |
RFBB (kΩ) |
CIN |
CBOOT |
CVCC |
CFF(3) |
400 |
3.3 |
22 |
2 × 22 µF |
4 × 10 µF |
33.2 |
14.3 |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
22 pF |
1000 |
3.3 |
8.2 |
1 × 22 µF |
2 × 10 µF |
33.2 |
14.3 |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
22 pF |
2200 |
3.3 |
2.2 |
1 × 22 µF |
2 × 10 µF |
33.2 |
14.3 |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
22 pF |
400 |
5 |
22 |
2 × 22 µF |
4 × 10 µF |
49.9 |
12.4 |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
22 pF |
1000 |
5 |
4.7 |
1 × 22 µF |
2 × 10 µF |
49.9 |
12.4 |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
22 pF |
2200 |
5 |
2.2 |
1 × 22 µF |
2 × 10 µF |
49.9 |
12.4 |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
22 pF |
(1) The switching frequencies listed here can be achieved in a number of ways
depending on the device variant. For RT devices see
Section 8.3.3. For MODE/SYNC devices see
Section 8.3.2.
(2) Inductor values are calculated based on typical VIN = 13.5 V.
(3) CFF to be placed in parallel with RFBT.
Table 9-3 Typical External Component
Values for Fixed Output LMR43620
ƒSW (kHz)(1) |
VOUT (V) |
L (µH)(2) |
NOMINAL COUT (RATED CAPACITANCE) |
MINIMUM COUT (RATED
CAPACITANCE) |
RFBT (Ω) |
RFBB (Ω)(3) |
CIN |
CBOOT |
CVCC |
400 |
3.3 |
10 |
3 × 22 µF |
1 × 47 µF |
0 |
DNP |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
1000 |
3.3 |
4.7 |
2 × 22 µF |
3 × 10 µF |
0 |
DNP |
2.2 µF + 1 × 100
nF |
100 nF |
1 µF |
2200 |
3.3 |
2.2 |
2 × 22 µF |
1 × 22 µF |
0 |
DNP |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
400 |
5 |
10 |
3 × 22 µF |
1 × 47 µF |
0 |
DNP |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
1000 |
5 |
4.7 |
2 × 22 µF |
3 × 10 µF |
0 |
DNP |
2.2 µF + 1 × 100
nF |
100 nF |
1 µF |
2200 |
5 |
2.2 |
2 × 22 µF |
1 × 22 µF |
0 |
DNP |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
(1) The switching frequencies listed here can be achieved in a number of ways
depending on the device variant. For RT devices see
Section 8.3.3. For MODE/SYNC devices see
Section 8.3.2.
(2) Inductor values are calculated
based on typical VIN = 13.5 V.
(3) DNP = Do Not Populate.
Table 9-4 Typical External Component Values for Fixed Output LMR43610
ƒSW (kHz)(1) |
VOUT (V) |
L (µH)(2) |
NOMINAL COUT (RATED CAPACITANCE) |
MINIMUM COUT (RATED
CAPACITANCE) |
RFBT (Ω) |
RFBB (Ω)(3) |
CIN |
CBOOT |
CVCC |
400 |
3.3 |
22 |
2 × 22 µF |
4 × 10 µF |
0 |
DNP |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
1000 |
3.3 |
4.7 |
1 × 22 µF |
2 × 10 µF |
0 |
DNP |
2.2 µF + 1 × 100
nF |
100 nF |
1 µF |
2200 |
3.3 |
2.2 |
1 × 22 µF |
2 × 10 µF |
0 |
DNP |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
400 |
5 |
22 |
2 × 22 µF |
4 × 10 µF |
0 |
DNP |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
1000 |
5 |
4.7 |
1 × 22 µF |
2 × 10 µF |
0 |
DNP |
2.2 µF + 1 × 100
nF |
100 nF |
1 µF |
2200 |
5 |
2.2 |
1 × 22 µF |
2 × 10 µF |
0 |
DNP |
4.7 µF + 1 × 100
nF |
100 nF |
1 µF |
(1) The switching frequencies listed here can be achieved in a number of ways
depending on the device variant. For RT devices see
Section 8.3.3. For MODE/SYNC devices see
Section 8.3.2.
(2) Inductor values are calculated based on typical VIN = 13.5 V.
(3) DNP = Do Not Populate.