TPS65166 Datasheet, PDF (22/45 Pages) Texas Instruments – Compact LCD Bias Supply for TFT-LCD TV Panels

TPS65166
SLVS976 – SEPTEMBER 2009.......................................................................................................................................................................................... www.ti.com
INDUCTOR VALUE
10 µH
10 µH
Table 3. Inductor Selection Boost Converter (continued)
COMPONENT SUPLIER
Sumida CDRH104R
Sumida CDRH8D43
SIZE (L×W×H mm)
10.3 × 10.5 × 4.0
8.3 × 8.3 × 4.5
Isat/DCR
4.4 A/26 mΩ
4 A/29 mΩ
Rectifier Diode Selection (Boost Converter)
To achieve high efficiency a Schottky diode should be used. The reverse voltage rating should be higher than the
maximum output voltage of the boost converter. The average rectified forward current I_avg, the Schottky diode
needs to be rated for, is equal to the output current I_out.
I_avg = I_out
(10)
Usually a Schottky diode with 2A maximum average rectified forward current rating is sufficient for most
applications. The Schottky rectifier can be selected with lower forward current capability depending on the output
current I_out, but has to be able to dissipate the power. The dissipated power is calculated according to the the
following equation:
P_D = I_avg × V_forward
(11)
V_r/I_avg
20V/2A
20V/2A
20V/3A
Table 4. Rectifier Diode Selection (Boost Converter)
V_forward
0.44V at 2A
0.44V at 2A
0.44V at 3A
R_θJA
25°C/W
75°C/W
46°C/W
SIZE
SMB
SMB
SMC
COMPONENT SUPPLIER
B220, DIODES Incorporated
SL22, Vishay Semiconductor
MBRS320, International Rectifier
Output Capacitor Selection (Boost Converter)
For the best output voltage filtering, low ESR ceramic output capacitors are recommended. Three 22µF or six
10µF ceramic output capacitors with sufficient voltage rating in parallel are adequate for most applications.
Additional capacitors can be added to improve the load transient regulation. See Table 5 for output capacitor
selection.
Table 5. Output Capacitor Selection (Boost Converter)
CAPACITOR
22µF/25V
10µF/25V
10µF/50V
COMPONENT SUPPLIER
Murata, GRM32ER61E226KE15
Murata, GRM31CR61E106KA12
Taiyo Yuden, UMK325BJ106MM
Setting the Output Voltage (Boost Converter)
The output voltage is set by an external resistor divider. A minimum current of 100µA through the feedback
divider provides good accuracy and noise covering. The resistors are calculated as:
V_s
= V_FB1
´
æ R1 ö
çè¹⁺ _R2 ÷ø
= 1.24 V
´
æ R1 ö
çè¹⁺ _R2 ÷ø
(12)
R2 =
V_{F B1}
1.24 V
=
» 12 kW
100 mA 100 mA
(13)
R1 = R2 ´
æ
ç
V_s
ö
- 1_÷
= R2
´
æ
ç
V_s
-
ö
1_÷
è ^VFB1 ø
è ^{1.24 V} ø
(14)
22
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