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參數資料
| 型號： | 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 |
| 文件頁數： | 9/15頁 |
| 文件大?。?/td> | 487K |
| 代理商： | TPS79428DGNR |
www.ti.com
APPLICATION INFORMATION
TPS794xx
GND
EN
NR
IN
OUT
V
IN
V
OUT
0.1
μ
F
0.01
μ
F
2.2
μ
F
External Capacitor Requirements
A 0.1-μF or larger ceramic input bypass capacitor, connected between IN and GND and located close to the
TPS794xx, is required for stability. It improves transient response, noise rejection, and ripple rejection. A
higher-value input capacitor may be necessary if large, fast-rise-time load transients are anticipated or the device
is located several inches from the power source.
TPS79401, TPS79418
TPS79425, TPS79428
TPS79430, TPS79433
SLVS349D–NOVEMBER 2001–REVISED OCTOBER 2004
The TPS794xx family of low-dropout (LDO) regulators has been optimized for use in noise-sensitive equipment.
The device features extremely low dropout voltages, high PSRR, ultralow output noise, low quiescent current,
and enable input to reduce supply currents to less than 1 μA when the regulator is turned off.
A typical application circuit is shown in Figure 22.
Figure 22. Typical Application Circuit
Like most low dropout regulators, the TPS794xx requires an output capacitor connected between OUT and GND
to stabilize the internal control loop. The minimum recommended capacitance is 2.2 μF. Any 2.2 μF or larger
ceramic capacitor is suitable.
The internal voltage reference is a key source of noise in an LDO regulator. The TPS794xx has an NR pin which
is connected to the voltage reference through a 250-k
internal resistor. The 250-k
internal resistor, in
conjunction with an external bypass capacitor connected to the NR pin, creates a low-pass filter to reduce the
voltage reference noise and, therefore, the noise at the regulator output. In order for the regulator to operate
properly, the current flow out of the NR pin must be at a minimum, because any leakage current creates an IR
drop across the internal resistor thus creating an output error. Therefore, the NR capacitor must have minimal
leakage current. The bypass capacitor should be no more than 0.1 μF to ensure that it is fully charged during the
quickstart time provided by the internal switch shown in the functional block diagram.
For example, the TPS79428 exhibits only 32 μV
RMS
of output voltage noise using a 0.1-μF ceramic NR capacitor
and a 2.2-μF ceramic output capacitor. Note that the output starts up slower as the bypass capacitance
increases due to the RC time constant at the NR pin that is created by the internal 250-k
resistor and external
capacitor.
9
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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 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節(jié):0.3 % 輸出端數量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格: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 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節(jié):0.3 % 輸出端數量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格: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 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節(jié):0.3 % 輸出端數量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格: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 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節(jié):0.3 % 輸出端數量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格: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 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節(jié):0.3 % 輸出端數量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
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