- 您现在的位置：买卖IC网 > PDF目录1841 > MAX1865TEEP+T (Maxim Integrated Products)IC PWR SUPPLY CONTROLLER 20QSOP PDF资料下载
参数资料
| 型号： | MAX1865TEEP+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 18/25页 |
| 文件大小： | 0K |
| 描述： | IC PWR SUPPLY CONTROLLER 20QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 应用： | 电源控制器 |
| 输入电压： | 4.5 V ~ 28 V |
| 电流 - 电源： | 1.4mA |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 20-QSOP |
| 包装： | 带卷 (TR) |
xDSL/Cable Modem Triple/Quintuple Output
Power Supplies
I PEAK =
V OUT V REF A VEA
V OUT ( NOMINAL ) R DS ( ON ) A VCS
where the error amplifier’s transconductance (g m ) is
100μS (see Electrical Characteristics ).
4) Finally, select the compensation capacitor:
where A VCS is the current-sense amplifier’s gain (4.9
typ), A VEA is the DC gain of the error amplifier (2000
typ), and V OUT(NOMINAL) is the output voltage set by
the feedback resistive-divider (internal or external).
C COMP ≤
1
2 π R COMP ? POLE ( OUT )
A V ( DC ) ≈ ≈
Since the output voltage is a function of the load cur-
rent and load resistance, the total DC loop gain
(A V(DC) ) is approximately:
I PEAK V REF R LOAD A VEA
I LOAD V OUT ( NOMINAL ) R DS ( ON ) A VCS
Boost-Supply Diode
A signal diode, such as the 1N4148, works well in most
applications. If the input voltage goes below 6V, use a
small 20mA Schottky diode for slightly improved effi-
ciency and dropout characteristics. Do not use large
power diodes, such as the 1N5817 or 1N4001, since
high junction capacitance can charge up VL to exces-
≈
400 × V REF R LOAD
V OUT ( NOMINAL ) R DS ( ON )
sive voltages.
Linear Regulator Controllers
Positive Output Voltage Selection
R 3 = R 4 ? ? OUT ? - 1 ?
The compensation capacitor (C COMP ) creates the dom-
inant pole. Due to the current-mode control scheme,
the output capacitor also creates a pole in the system
that is a function of the load resistance. As the load
resistance increases, the frequency of the output
capacitor’s pole decreases. However, the DC loop gain
increases with larger load resistance, so the unity gain
bandwidth remains fixed. Additionally, the compensa-
tion resistor and the output capacitor’s ESR both gener-
ate zeros. Therefore, to achieve stable operation, use
the following procedure to properly compensate the
system:
1) First, select the desired crossover frequency. The
crossover frequency must be less than both 1/5th
the switching frequency and 1/3rd the zero frequen-
cy set by the output capacitor’s ESR:
The MAX1864/MAX1865s’ positive linear regulator out-
put voltages are set by connecting a voltage-divider
from the output to FB_ to GND (Figure 6). Select R4 in
the 5k Ω to 50k Ω range. Calculate R3 with the following
equation:
? ? V ? ?
? ?
? ? V FB ? ?
where V FB = 1.24V, and V OUT may range from 1.24V to
30V.
Negative Output Voltage Selection (MAX1865)
The MAX1865’s negative output voltage is set by con-
necting a voltage-divider from the output to FB5 to a
positive voltage reference (Figure 6). Select R6 in the
5k Ω to 50k Ω range. Calculate R5 with the following
? c ≤
1 ? SW
6 π C OUT ESR
R 5 = R 6 ? OUT ?
and
R 5
2) Next, determine the pole set by the output capacitor
and the load resistor:
equation:
? V ?
? V REF ?
? POLE ( OUT ) = =
1
2 π C OUT R LOAD
I LOAD ( MAX )
2 π C OUT V OUT
where V REF is the positive reference voltage used, and
V OUT may be set between 0 and -20V.
If the negative regulator is used, the OUT pin must be
connected to a voltage supply between 2V and 5V that
3) Determine the compensation resistor required to set
the desired crossover frequency:
can source at least 25mA. Typically, the OUT pin is
connected to the step-down converter ’s output.
R COMP =
2000 × ? c
g m A V ( DC ) ? POLE ( OUT )
However, if the step-down converter’s output voltage is
set higher than 5V, OUT may be connected to one of
the positive linear regulators with an output voltage
between 2V and 5V.
18
______________________________________________________________________________________
相关PDF资料 |
PDF描述 |
|---|---|
| MAX1873REEE+T | IC CNTRLR CHARGE LI+ 16-QSOP |
| MAX1874ETE+ | IC LI+ CHARGER DUAL-IN 16-TQFN |
| MAX1875AEEG+ | IC REG CTRLR BUCK PWM VM 24-QSOP |
| MAX1876EEG+T | IC REG CTRLR BUCK PWM VM 24-QSOP |
| MAX1878ETC+ | IC REG BUCK BST SYNC ADJ 12TQFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1865UEEP | 功能描述:电流和电力监控器、调节器 RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX1865UEEP-T | 功能描述:电流和电力监控器、调节器 RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX1868EGL | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX1868ETL | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX1869EGL | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
发布紧急采购，3分钟左右您将得到回复。