- 您現(xiàn)在的位置：買(mǎi)賣(mài)IC網(wǎng) > PDF目錄384709 > MAX881 (Maxim Integrated Products, Inc.) Low-Noise Bias Supply in レMAX with Power-OK for GaAsFET PA PDF資料下載
參數(shù)資料
| 型號(hào)： | MAX881 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Low-Noise Bias Supply in レMAX with Power-OK for GaAsFET PA |
| 中文描述： | 低噪聲偏置電源在レ最大的功率為GaAsFET功率放大器行 |
| 文件頁(yè)數(shù)： | 7/8頁(yè) |
| 文件大小： | 111K |
| 代理商： | MAX881 |
M
Low-Noise Bias S upply in μMAX
with Power-OK for GaAsFET PA
_______________________________________________________________________________________
7
Capac itors
Use capacitors with a low effective series resistance
(ESR) to maintain a low dropout voltage (V
IN
- |V
OUT
|.
The overall dropout voltage is a function of the output
resistance of the charge pump and the voltage drop
across the linear regulator (N-channel pass transistor).
At the 100kHz charge-pump switching frequency, out-
put resistance is a function of the value of C1 and the
ESR of C1 and C2. Therefore, increasing C1 and mini-
mizing the ESR of the charge-pump capacitors mini-
mizes dropout voltage.
The output resistance of the entire circuit (in dropout) is
approximately:
R
OUT
= R
O
+ 4 x ESR
C1
+ ESR
C2
+ 1 / (f
S
x C1)
+ R
(linear regulator)
Where R
(linear regulator)
(the output impedance of the
linear regulator) is approximately 2
and R
O
(the resis-
tance of the internal switches) is typically 10
. When
regulating, the output resistance of the circuit is simply
the linear-regulator load regulation (2mV/mA).
C1, C2, and C3 should be 0.22μF capacitors with less
than 0.4
ESR. C4 should be a 4.7μF capacitor with
less than 0.1
ESR. Larger capacitor values can be
used (C1 = C2 = C3 = 1μF, C4 = 10μF) to reduce out-
put noise and ripple (1mVp-p), at the expense of cost
and board space. All capacitors should be either
ceramic or surface-mount chip tantalum (Figures 3a
and 3b).
Layout and Grounding
Good layout is important for good noise performance.
To optimize the layout:
1) Mount all components as close together as possible.
2) Keep traces short to minimize parasitic inductance
and capacitance, especially connections to FB.
3) Use a ground plane.
Noise and Ripple Measurement
Accurately measuring the output noise and ripple is a
challenge. Slight momentary differences in ground
potential between the circuit and the oscilloscope
(which result from the charge pump’s switching action)
cause ground currents in the probes’ wires, inducing
sharp voltage spikes. For best results, measure directly
across the output capacitor (C4). Do not use the
ground lead of the probe; instead, remove the probe’s
tip cover and touch the ground ring on the probe
directly to C4’s ground terminal. This direct connection
gives the most accurate noise and ripple measurement.
NEGOUT
SHDN
C1-
C1+
POK
FB
C3
0.22
μ
F
C2
0.22
μ
F
C1
0.22
μ
F
C4
4.7
μ
F
V
IN
OUT
R2
R1
IN
GND
MAX881R
ON
OFF
Figure 4. Adjustable Output Configuration
TRANSISTOR COUNT: 413
Chip Information
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX881R | Low-Noise Bias Supply in レMAX with Power-OK for GaAsFET PA |
| MAX884CPA | 5V/3.3V or Adjustable, Low-Dropout, Low IQ, 200mA Linear Regulators |
| MAX884 | 5V/3.3V or Adjustable, Low-Dropout, Low IQ, 200mA Linear Regulators |
| MAX884MJA | 5V/3.3V or Adjustable, Low-Dropout, Low IQ, 200mA Linear Regulators |
| MAX884CSA | Octal Transparent D-type Latches With 3-State Outputs 20-CFP -55 to 125 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX8810AETM+ | 功能描述:電流型 PWM 控制器 VRD11/10 K8 Rev. F 2/3/4-Phase PWM Ctlr RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| MAX8810AETM+T | 功能描述:電流型 PWM 控制器 VRD11/10 K8 Rev. F 2/3/4-Phase PWM Ctlr RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| MAX8811EEE+ | 功能描述:功率驅(qū)動(dòng)器IC High-Speed Dual Phase Driver RoHS:否 制造商:Micrel 產(chǎn)品:MOSFET Gate Drivers 類(lèi)型:Low Cost High or Low Side MOSFET Driver 上升時(shí)間: 下降時(shí)間: 電源電壓-最大:30 V 電源電壓-最小:2.75 V 電源電流: 最大功率耗散: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| MAX8811EEE+T | 功能描述:功率驅(qū)動(dòng)器IC High-Speed Dual Phase Driver RoHS:否 制造商:Micrel 產(chǎn)品:MOSFET Gate Drivers 類(lèi)型:Low Cost High or Low Side MOSFET Driver 上升時(shí)間: 下降時(shí)間: 電源電壓-最大:30 V 電源電壓-最小:2.75 V 電源電流: 最大功率耗散: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| MAX8814ETA+ | 制造商:Maxim Integrated Products 功能描述:CHGR LI-ION/LI-POL 570MA 4.2V 8TDFN EP - Rail/Tube 制造商:Rochester Electronics LLC 功能描述: |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。