5V/3.3V/3V/Adjustable-Output, 1A,

Step-Down, PWM, Switch-Mode DC-DC Regulators

4

_______________________________________________________________________________________

______________________________________________________________Pin Description

PIN

FUNCTION

11

5, 7,

10, 12

1, 2,

3, 4

6

9

Shutdown is achieved by pulling SHUT low. Leave SHUT floating for normal operation.

Error-amplifier output. A series RC network connected to this pin compensates the device. Output swing

nize the device to an external TTL clock in the 115kHz to 170kHz range.

Ground requires a short, low-noise connection to ensure good load regulation. The internal reference is referred

to GND, so errors at this pin are multiplied by the error amplifier. Use thick copper for low thermal resistance.

(See Note 7 in

NAME

GND

SHUT

__________Applications Information

Although the MAX830–MAX833 are high-efficiency

step-down voltage converters, certain precautions are

required to avoid excessive chip temperature (the

+125°C). The 16-pin SO package has thermal resis-

tance of +55°C/W when mounted properly; this limits

continuous chip power dissipation to the 1W range.

When installing these chips:

1) Use wide and, if possible, thick copper traces to

connect the leads (especially the GND pins) to

reduce thermal resistance.

2) Bond the package firmly to the board or use a clip-

style heatsink. A very small drop of thermal paste

between the chip package and the copper ground

plane is also helpful.

3) Confirm that the range of device operation is such

that the chip temperature does not exceed the

determined from Tables 1 and 2.

Tables 1 and 2 show numbers for maximum allowed

limit. If the input voltage range, ambient temperature,

and/or output voltage setting allow for an unsafe level

of load current, limit the load current to a safe value by

GND. With no external resistor, the preset switch cur-

rent limit (typically 1.7A) will limit the load current to

about 1.3A. Table 1 shows safe operating load cur-

rents for the MAX830 for various values of input and

output voltage and at three different ambient tempera-

Table 2 shows the same information, but for the fixed

output voltage MAX831, MAX832, and MAX833.

When consulting these tables, note that power surges

of less than 30sec need not be considered from a ther-

mal standpoint. It is important for proper regulation,

however, that a power surge not require a peak switch

current exceeding the 1.2A (min) switch current limit.

For highest efficiency, the inductor series resistance

should be 0.4

the following formula:

preset switch current limit);

and from Table 1:

(i.e., operation is safe).

SENSE

(MAX831/

2/3)

8

For the MAX831/MAX832/MAX833, SENSE input is the internal error amplifier’s input, and should be

is low.

13, 14,

15, 16

Internal power switch output (rated for 1A load current)

FB

(MAX830)

For the MAX830, the FB input is the internal error amplifier's input, and should be connected to the mid-