MAX667 Maxim, MAX667 Datasheet - Page 6

• Manufacturer Part Number: MAX667
• Description: +5V/Programmable Low-Dropout Voltage Regulator
• Manufacturer: Maxim

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.
+5V/Programmable Low-Dropout
Voltage Regulator
6
Figure 6. Quiescent-Current Reduction Below Dropout
Figure 5. Alternative Stability Scheme Using Resistor R
_______________________________________________________________________________________
8
IN
6
8
SET
IN
6
SET
MAX667
4
GND
MAX667
4
GND
SHDN
5
OUT
DD
SHDN
5
OUT
2
1
47k
2
R1
C1
10 F
+5V OUT
R
10 F
+5V OUT
C2
0.1 F
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: [phone], fax: [phone]).
The MAX667 uses a PNP output transistor. When the
input voltage falls below the desired output voltage, the
Figure 7. Connection for Minimum Quiescent Current Near
Dropout
Figure 8. Quiescent Current Below Dropout for Circuit of
Figure 2
8
5
10
IN
SHDN
8
6
4
2
0
0
GND
4
V SHDN = 0V
MAX667
1
1
INPUT VOLTAGE (V)
DD
2
OUT
SET
1M
R3
3
2
6
4
Battery Drain
R2
1M
R1
332k
5
C1
10 F
6
+5V OUT