put-capacitor ESR and this series resistance should, at

minimum, meet the requirements shown in Figure 4.

An upper limit to the output-capacitor ESR is important

only if step changes to the load are anticipated. Higher

ESR results in higher-amplitude output-voltage tran-

sients when the output current is varied. A Sanyo

OS-CON capacitor, whose ESR is nearly flat over tem-

perature (and is low to begin with), in series with the

appropriate resistor ensures the best load-transient

performance. A less expensive alternative is to use a

tantalum capacitor in series with the resistor.

In most cases, inexpensive aluminum-electrolytic

capacitors work well with the MAX667 over their entire

temperature range, having sufficient ESR to ensure sta-

bility without the need for a series resistor. The ESR of

aluminium electrolytics rises, often dramatically, as

temperature decreases. For surface-mount applica-

tions, certain tantalum capacitors have sufficient ESR;

an example is the TAJB106K016 chip capacitor made

by AVX (phone: (803) 448-9411, fax: (803) 448-1943).

Battery Drain

The MAX667 uses a PNP output transistor. When the

input voltage falls below the desired output voltage, the

+5V/Programmable Low-Dropout

Voltage Regulator

6

_______________________________________________________________________________________

MAX667

GND

SHDN

SET

OUT

R1

47k

DD

+5V OUT

IN

8

64

5

2

1

C1

10

µF

C2

0.1

µF

Figure 6. Quiescent-Current Reduction Below Dropout

MAX667

DD

GND

OUT

R3

1M

R1

332k

R2

1M

SET

+5V OUT

IN

8

41

2

6

C1

10

µF

SHDN

5

Figure 7. Connection for Minimum Quiescent Current Near

Dropout

10

0

0

1

2

3

456

2

INPUT VOLTAGE (V)

4

6

8

VSHDN = 0V

Figure 8. Quiescent Current Below Dropout for Circuit of

Figure 2

MAX667

SHDN

SET

GND

OUT

R

+5V OUT

IN

82

10

µF

64

5

Figure 5. Alternative Stability Scheme Using Resistor R