+5V/Programmable Low-Dropout
Voltage Regulator
MAX667
8
+5V OUT
2
C1
10μF
+5V OUT
8
IN
OUT
2
IN
OUT
MAX667
R
10μF
5
SHDN
MAX667
R2
1M
SET
DD
1
6
GND
SET
6
GND
4
SHDN
5
4
R1
332k
R3
1M
Figure 5. Alternative Stability Scheme Using Resistor R
Figure 7. Connection for Minimum Quiescent Current Near
Dropout
8
IN
OUT
2
C1
10μF
+5V OUT
QUIESCENT CURRENT (mA)
8
VSHDN = 0V
MAX667
6
DD
SET
6
GND
4
SHDN
5
1
4
2
R1
47k
C2
0.1μF
0
0
1
2
3
4
5
6
INPUT VOLTAGE (V)
Figure 6. Quiescent-Current Reduction Below Dropout
Figure 8. Quiescent Current Below Dropout for Circuit of
Figure 2
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
aluminum electrolytics rises, often dramatically, as tem-
perature decreases. For surface-mount applications,
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
6
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MAX667-Fg 8
10
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
