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參數(shù)資料
| 型號(hào)： | TPS79428DGNR |
| 廠商： | Texas Instruments, Inc. |
| 英文描述： | ULTRALOW-NOISE, HIGH PSRR, FAST RF 250-mA LOW-DROPOUT LINEAR REGULATORS |
| 中文描述： | 超低噪聲，高PSRR，快速射頻250毫安低壓降線性穩(wěn)壓器 |
| 文件頁(yè)數(shù)： | 11/15頁(yè) |
| 文件大?。?/td> | 487K |
| 代理商： | TPS79428DGNR |
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Programming the TPS79401 Adjustable LDO Regulator
The output voltage of the TPS79401 adjustable regulator is programmed using an external resistor divider as
shown in Figure 24. The output voltage is calculated using:
VOUT
VREF
1
R1
R2
(3)
R1
VOUT
VREF
1
R2
(4)
C1
(3 x 10
–7
) x (R1
(R1 x R2)
R2)
(5)
22 pF
15 pF
15 pF
OUTPUT VOLTAGE
PROGRAMMING GUIDE
OUTPUT
VOLTAGE
2.5 V
3.3 V
3.6 V
R1
R2
C1
31.6 k
49.9 k
59 k
30.1 k
30.1 k
30.1 k
Not Available on the DCQ package.
TPS794xx
GND
NR
FB
IN
OUT
EN
V
IN
V
OUT
R1
C1
R2
1
μ
F
2.2
μ
F
0.01
μ
F
Regulator Protection
The TPS794xx PMOS-pass transistor has a built-in back diode that conducts reverse current when the input
voltage drops below the output voltage (e.g., during power-down). Current is conducted from the output to the
input and is not internally limited. If extended reverse voltage operation is anticipated, external limiting might be
appropriate.
TPS79401, TPS79418
TPS79425, TPS79428
TPS79430, TPS79433
SLVS349D–NOVEMBER 2001–REVISED OCTOBER 2004
where:
Resistors R1 and R2 should be chosen for approximately 40-μA divider current. Lower value resistors can be
used for improved noise performance, but the device wastes more power. Higher values should be avoided as
leakage current at FB increases the output voltage error. The recommended design procedure is to choose
R2 = 30.1 k
to set the divider current at 40 μA, C1 = 15 pF for stability, and then calculate R1 using:
V
REF
= 1.2246 V typ (the internal reference voltage).
In order to improve the stability of the adjustable version, it is suggested that a small compensation capacitor be
placed between OUT and FB. For voltages < 1.8 V, the value of this capacitor should be 100 pF. For voltages
> 1.8 V, the approximate value of this capacitor can be calculated as:
The suggested value of this capacitor for several resistor ratios is shown in the table below. If this capacitor is
not used (such as in a unity-gain configuration) or if an output voltage < 1.8 V is chosen, then the minimum
recommended output capacitor is 4.7 μF instead of 2.2 μF.
Figure 24. TPS79401 Adjustable LDO Regulator Programming
The TPS794xx features internal current limiting and thermal protection. During normal operation, the TPS794xx
limits output current to approximately 925 mA. When current limiting engages, the output voltage scales back
linearly until the overcurrent condition ends. While current limiting is designed to prevent gross device failure,
care should be taken not to exceed the power dissipation ratings of the package or the absolute maximum
voltage rating of the device. If the temperature of the device exceeds approximately 165
°
C, thermal-protection
circuitry shuts it down. Once the device has cooled down to below approximately 140
°
C, regulator operation
resumes.
11
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| TPS79428DGNRG4 | 功能描述:低壓差穩(wěn)壓器 - LDO High PSRR Fast RF High-Enable 250-mA RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動(dòng)電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| TPS79428DGNT | 功能描述:低壓差穩(wěn)壓器 - LDO High PSRR Fast RF High-Enable 250-mA RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動(dòng)電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| TPS79428DGNTG4 | 功能描述:低壓差穩(wěn)壓器 - LDO High PSRR Fast RF High-Enable 250-mA RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動(dòng)電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| TPS79430DCQ | 功能描述:低壓差穩(wěn)壓器 - LDO High PSRR Fast RF High-Enable 250-mA RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動(dòng)電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| TPS79430DCQG4 | 功能描述:低壓差穩(wěn)壓器 - LDO Sgl Output 250mA Fixed 3.0V Hi PSRR RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動(dòng)電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
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