TPS7A39
ZHCSGP0A –JULY 2017–REVISED SEPTEMBER 2017
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Application Information (接下页)
表 4 and 表 5 show the resistor combinations for several common output voltages using commercially available,
1% tolerance resistors.
表 4. Recommended Feedback-Resistor Values for the Positive LDO
FEEDBACK RESISTOR VALUES(1)
TARGETED OUTPUT
VOLTAGE (V)
CALCULATED OUTPUT
VOLTAGE (V)
R1P (kΩ)
2.67
5.23
11.0
15.4
17.8
32.4
66.5
90.9
115
R2P (kΩ)
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
1.5
1.8
1.50
1.80
2.49
3.00
3.29
5.02
9.07
12.0
14.8
23.8
29.8
2.5
3.0
3.3
5.0
9.0
12.0
15.0
24.0
30.0
191
243
(1) R1P is connected from OUTP to FBP, R2P is connected from FBP to GND; see the Setting the Output Voltages on Adjustable Devices
section.
表 5. Recommended Feedback-Resistor Values for the Negative LDO
FEEDBACK RESISTOR VALUES(1)
TARGETED OUTPUT
VOLTAGE (V)
CALCULATED OUTPUT
VOLTAGE (V)
R1N (kΩ)
2.55
12.7
15.0
21.0
25.5
28.0
42.2
75.0
100
R2N (kΩ)
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
-0.3
-1.5
-0.303
-1.51
-1.78
-2.49
-3.03
-3.33
-5.04
-8.91
-11.9
-15.1
-23.8
-30.3
-1.8
-2.5
-3.0
-3.3
-5.0
-9.0
-12.0
-15.0
-24.0
-30.0
127
200
255
(1) R1N is connected from OUTN to FBN, R2N is connected from FBN to BUF; see the Setting the Output Voltages on Adjustable Devices
section.
8.1.2 Capacitor Recommendations
The device is designed to be stable using low equivalent series resistance (ESR) ceramic capacitors at the input
and output pins. The device is also designed to be stable with aluminum polymer and tantalum polymer
capacitors with ESR < 75 mΩ.
Electrolytic capacitors (along with higher ESR polymer capacitors) can also be used if capacitors (meeting the
minimum capacitance and ESR requirements ) are used in parallel.
Take the effective ESR for stability when the impedance of the capacitor is at its minimum. At the minimum level,
the capacitance and parasitic inductance cancel each other and provides the DC ESR.
Ceramic capacitors that employ X7R-, X5R-, and COG-rated dielectric materials provide relatively good
capacitive stability across temperature, whereas the use of Y5V-rated capacitors is discouraged because of large
variations in capacitance.
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