Rainbow-electronics MAX1821 Manual do Utilizador descarregar pdf (Página 8)

MAX1820/MAX1821

WCDMA Cellular Phone 600mA

Buck Regulators

8 _______________________________________________________________________________________

0.1 1 10

OUTPUT SWITCHING HARMONICS

vs. FREQUENCY

= 3.8V, V

OUT

= 3.4V, I

LOAD

= 600mA)

MAX1820/21 toc19

FREQUENCY (MHz)

HARMONICS (mV

RMS

)

1.6

1.2

0.8

0.4

0.1 1 10

OUTPUT SWITCHING HARMONICS

vs. FREQUENCY

= 3.8V, V

OUT

= 1.8V, I

LOAD

= 300mA)

MAX1820/21 toc20

FREQUENCY (MHz)

HARMONICS (mV

RMS

)

0.8

0.4

1.6

1.2

Pin Description

MAX1820

UCSP

MAX1820

µMAX

MAX1821

UCSP

MAX1821

µMAX

NAME FUNCTION

A1 1 A1 1 SKIP

PWM/Skip-Mode Input. Drive with logic 0 to use PWM at medium

and heavy loads and pulse skipping at light loads. Drive with

logic 1 to force PWM at all loads.

A2 2 A2 2 COMP

Compensation. Typically, connect an 82kΩ (for MAX1821) or

43kΩ (for MAX1820) series resistor and 330pF capacitor from

this pin to GND to stabilize the regulator.

A3 3 ——OUT Output Voltage Sense Input. Connect OUT directly to the output.

0.1 1 10

OUTPUT SWITCHING HARMONICS

vs. FREQUENCY

= 4.2V, V

OUT

= 0.4V, I

LOAD

= 30mA)

MAX1820/21 toc21

FREQUENCY (MHz)

HARMONICS (mV

RMS

)

0.8

0.4

1.6

1.2

FREQUENCY (MHz)

OUTPUT NOISE (V

= 3.6V,

OUT

= 1.8V, I

OUT

= 300mA)

4.0

3.0

1.0

2.0

MAX1820/21 toc22

0.1 1 10

100

250

NOISE (µV/√Hz)

Typical Operating Characteristics (continued)

= +25°C, unless otherwise noted.)

1 2 3 4 5 6 7 8 9 10 11 12 13 ... 17 18

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