Datasheet

LM2650
SNVS133C –JUNE 1999–REVISED APRIL 2013 www.ti.com
Table 2. Toroidal Inductors Using Cores from MICROMETALS, INC.
Core Number Core Material Wire Gauge Number of Strands Number of Turns
15μH T38 −52 AWG # 23 1 21
20μH T38 −52 AWG # 23 1 25
33μH T50 −52 AWG # 21 1 41
40μH T50 (B) −18 AWG # 21 1 41
Table 3. Components for Typical 200 kHz Applications
Input Voltage 7V to 18V IN
Applicable Cell Stacks 8 to 12 Cell NiCd or NiMh, 3 to 4 Cell Li Ion, 8 to 11 Cell Alkaline, 6 Cell Lead Acid
Output 5V, 3A Out 3.3V, 3A out
Input Capacitor C
IN
2 x 22 μF, 35V AVX TPS 2 x 22 μF, 35V AVX TPS
Series or Sprague 593D Series Series or Sprague 593D Series
Inductor L1 20μH (See Table 2) 15μH (See Table 2)
Output Capacitor C
OUT
3x220 μF, 10V AVX TPS 3x220 μF, 10V AVX TPS
Series or Sprague 593D Series Series or Sprague 593D Series
Feedback Resistors R1 and R2 R1 = 75kΩ, 1%, R1 = 41.2kΩ, 1%,
R2 = 24.9kΩ, 1%, R2 = 24.9kΩ, 1%,
Compensation Components R
C
, C
C
, R
C
= 53.6 kΩ, C
C
= 2.7 nF, R
C
= 33.2 kΩ, C
C
= 3.9 nF,
R
3
, and C
10
R
3
= 4.02 kΩ, C
10
= 4.7 nF R
3
= 3.01 kΩ, C
10
= 6.8 nF
Sleep Resistors R
SIA
and R
SOA
R
SIA
= 33 kΩ, R
SOA
= 200 kΩ R
SIA
= 47 kΩ, R
SOA
= 91 kΩ
Frequency Adjusting Resistor R
FA
R
FA
= 24.9 kΩ R
FA
= 24.9 kΩ
Figure 19. An Efficient, 2% Accurate 5V to 3.3V Converter
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