Datasheet

MAX667
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: [phone], fax: [phone]).
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 SHDNSET
OUT
R1
47k
DD
+5V OUTIN
8
645
2
1
C1
10μF
C2
0.1μF
Figure 6. Quiescent-Current Reduction Below Dropout
MAX667
DDGND
OUT
R3
1M
R1
332k
R2
1M
SET
+5V OUTIN
8
41
2
6
C1
10μF
SHDN
5
Figure 7. Connection for Minimum Quiescent Current Near
Dropout
10
0
0123456
2
MAX667-Fg 8
INPUT VOLTAGE (V)
QUIESCENT CURRENT (mA)
4
6
8
V
SHDN = 0V
Figure 8. Quiescent Current Below Dropout for Circuit of
Figure 2
MAX667
SHDNSET GND
OUT
R
+5V OUTIN
82
10μF
645
Figure 5. Alternative Stability Scheme Using Resistor R