Rainbow-electronics MAX1664 Manual de usuario descargar pdf (Pagina 12)

MAX1664

12 ______________________________________________________________________________________

Diode Selection

The MAX1664’s high switching frequency requires fast

diodes. Schottky diodes such as the MBR0520L and

MBR0540L (Motorola) are recommended because they

have the necessary power ratings in a low-height SOD-

123 package. Also recommended is the MBRM5817

which is 1.1mm high. Use a Schottky diode with a for-

ward current rating greater than:

For the positive output of DC-DC 2, use a Schottky

diode with a voltage rating that exceeds V

OUT2+

. For

the negative output, use a Schottky diode with a rating

that exceeds V

+ V

OUT2-

. See Table 3 for more

information on Schottky diode manufacturers.

Filter Capacitor Selection

An output filter capacitor’s ESR and size can greatly

influence a switching converter’s output ripple, as

shown in the following equation.

V I x R I

DC-DC 1 t

V V - V

V V

DC-DC 2 t

2 f

RIPPLE(PK PK) PEAK ESR OUT

OUT

DC-DC 1

OUT1 F IN

OUT1 F

DC-DC 1

−

≅ +

























I V

OUT OUT

0 9

Table 2. Typical DC-DC 2 Operation

Note: Absolute maximum peak current at LX2P and LX2N is 750mA.

Active Matrix Liquid Crystal Display

(AMLCD) Supply

INDUCTOR PEAK

CURRENT*

(mA)

DC-DC 2(MAX)

(kHz)

OUT2-(MAX)

(mA)

OUT2+(MAX)

(mA)

(µH)

BPCLK

(kHz)

(V)

OUT2-

(V)

OUT2+

(V)

50048015104.730.05.0-10+20

55040018104.725.05.0-10+20

64036020114.722.55.0-10+20

67948017102.730.04.5-10+20

4504801284.730.04.5-10+20

5004001484.725.04.5-10+20

5803601694.722.54.5-10+20

496480844.730.03.3-10+20

340480544.730.03.3-10+20

5834001062.725.03.3-10+20

370400744.725.03.3-10+20

6433601262.722.53.3-10+20

425360844.722.53.3-10+20

451480632.730.03.0-10+20

300480434.730.03.0-10+20

530400842.725.03.0-10+20

340400524.725.03.0-10+20

5853601052.722.53.0-10+20

385360634.722.53.0-10+20

60036043204.722.55.0-5+15

55036035154.722.54.5-5+15

64336027102.722.53.3-5+15

4253601974.722.53.3-5+15

5853602382.722.53.0-5+15

3753601564.722.53.0-5+15

1 2 ... 7 8 9 10 11 12 13 14 15 16

(AMLCD) Supply 1

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Rainbow-electronics MAX1664 Manual de usuario Pagina 12

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