Low-Profile, 5V/12V or Adjustable, Step-Up

DC-DC Converters for Flash Memory/PCMCIA Cards

8

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Detailed Description

The remainder of this document contains the detailed

information you’ll need to design a circuit that differs

from the two Standard Application Circuits. If you are

using one of the predesigned circuits, the following

sections are purely informational.

The MAX606/MAX607 CMOS, step-up DC-DC convert-

ers employ a current-limited pulse-frequency control

scheme. This control scheme regulates a boost topolo-

gy to convert input voltages between 3V and 5.5V into

either a pin-programmable 5V/12V output, or an

performance over all input and output voltages, and

guarantees output accuracy to ±4%.

The ultra-high switching frequency (typically 1MHz for

the MAX606 and 0.5MHz for the MAX607) permits the

use of extremely small external components, making

these converters ideal for use in Types 1, 2, and 3 flash

memory and PCMCIA applications.

Pulse-Frequency-Modulation

Control Scheme

The MAX606/MAX607 employ a proprietary, current-

limited control scheme that combines the ultra-low sup-

ply current of traditional pulse-skipping converters with

the high full-load efficiency of current-mode pulse-

width-modulation converters. This particular control

scheme is similar to the one used in previous current-

limited devices (which governed the switching current

via maximum on-time, minimum off-time, and current

limit), except it varies the on and off times according to

the input and output voltages. This important feature

enables the MAX606/MAX607 to achieve ultra-high

switching frequencies while maintaining high output

accuracy, low output ripple, and high efficiency over a

wide range of loads and input/output voltages.

Figure 3 shows the functional diagram of the MAX606/

MAX607. The internal power MOSFET is turned on when

the error comparator senses that the output is out of reg-

ulation. The power switch stays on until either the timing

circuit turns it off at the end of the on-time, or the switch

current reaches the current limit. Once off, the switch

remains off during the off-time. Subsequently, if the out-

put is still out of regulation, another switching cycle is ini-

tiated. Otherwise, the switch remains turned off as long

as the output is in regulation.

Table 1. Suggested Components for 12V

Standard Application Circuit of Figure 2

Table 2. Suggested Components for 5V

Standard Application Circuit of Figure 1

DESIGNATION

MAX606

MAX607

L1

5µH inductor

Dale ILS-3825-XX

10µH inductor

Sumida CLS62-100

D1

0.5A, 20V diode

Motorola MBR0520L

0.5A, 20V diode

Motorola MBR0520L

C1

0.1µF ceramic cap.

0.1µF ceramic cap.

C2

2 x 0.68µF ceramic cap.

Marcon

THCR20E1E684Z

2.2µF ceramic cap.

Marcon

THCR30E1E225M

C3

2 x 0.68µF ceramic cap.

Marcon

THCR20E1E684Z

2 x 1µF ceramic cap.

Marcon

THCR30E1E105M

C4

10nF ceramic cap.

10nF ceramic cap.

SUPPLIER

PHONE

FAX

Dale Inductors

605-668-4131

605-665-1627

Marcon/United

Chemi-Con

708-696-2000

708-518-9985

Sumida USA

708-956-0666

708-956-0702

Sumida Japan

03-607-5111

03-607-5144

Table 3. Component Suppliers

DESIGNATION

MAX606

MAX607

L1

5µH, 1A inductor

Dale ILS-3825-XX

10µH, 0.7A inductor

Sumida CLS62B-100

D1

0.5A, 20V diode

Motorola MBR0520L

0.5A, 20V diode

Motorola MBR0520L

C1

0.1µF ceramic cap.

0.1µF ceramic cap.

C2

2 x 0.68µF ceramic cap.

Marcon

THCR20E1E684Z

2.2µF ceramic cap.

Marcon

THCR30E1E225M

C3

4.7µF ceramic cap.

Marcon

THCR30E1E475M

4.7µF ceramic cap.

Marcon

THCR30E1E475M

C4

10nF ceramic cap.

10nF ceramic cap.

Motorola

602-244-3576

602-244-4015