Rainbow-electronics MAX1715 Manual do Utilizador descarregar pdf (Página 12)

MAX1715

Ultra-High Efficiency, Dual Step-Down

Controller for Notebook Computers

12 ______________________________________________________________________________________

current-limit threshold, and the minimum off-time one-

shot has timed out.

On-Time One-Shot (TON)

The heart of the PWM core is the one-shot that sets the

high-side switch on-time for both controllers. This fast,

low-jitter, adjustable one-shot includes circuitry that

varies the on-time in response to battery and output

voltage. The high-side switch on-time is inversely pro-

portional to the battery voltage as measured by the V+

input, and proportional to the output voltage. This algo-

rithm results in a nearly constant switching frequency

despite the lack of a fixed-frequency clock generator.

The benefits of a constant switching frequency are

twofold: first, the frequency can be selected to avoid

noise-sensitive regions such as the 455kHz IF band;

second, the inductor ripple-current operating point

remains relatively constant, resulting in easy design

methodology and predictable output voltage ripple.

The on-times for side 1 are set 15% higher than the

REF

AGND

REF

OUT2

FB2

20Ω

PGND

OUTPUT2

2.5V

DL2

LX2

ZERO

CROSSING

CURRENT

LIMIT

PWM

CONTROLLER

(SEE FIGURE 3)

DH2

BST2

LIM_

V+

OUT1

FB1

SKIP

TON

ON1

ON2

OUTPUT1

1.8V

5V INPUT

DL1

LX1

ZERO

CROSSING

CURRENT

LIMIT

DH1

LIM_

BATTERY

4.5V TO 28V

5µA

BST1

V+

PWM

CONTROLLER

(SEE FIGURE 3)

MAX1715

5µA

GOOD

Figure 2. Functional Diagram

1 2 ... 7 8 9 10 11 12 13 14 15 16 17 ... 24 25

Comentários a estes Manuais

Sem comentários

Rainbow-electronics MAX1715 Manual do Utilizador Página 12

Comentários a estes Manuais

Manuais e produtos relacionados com Sensores Rainbow-electronics MAX1715