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| 型号： | MAX662ACPA+ |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 稳压器 |
| 英文描述： | 12V, 30mA Flash Memory Programming Supply |
| 中文描述： | SWITCHED CAPACITOR REGULATOR, 500 kHz SWITCHING FREQ-MAX, PDIP8 |
| 封装： | 0.300 INCH, PLASTIC, DIP-8 |
| 文件页数： | 4/6页 |
| 文件大小： | 75K |
| 代理商： | MAX662ACPA+ |
MAX662A
_______________Detailed Description
Operating Principle
The MAX662A provides a regulated 12V output voltage
at 30mA from a 5V ±5% power supply, making it ideal
for flash EEPROM programming applications. It uses
internal charge pumps and external capacitors to gen-
erate +12V, eliminating inductors. Regulation is provid-
ed by a pulse-skipping scheme that monitors the
output voltage level and turns on the charge pumps
when the output voltage begins to droop.
Figure 1 shows a simplified block diagram of the
MAX662A. When the S1 switches are closed and the
S2 switches are open, capacitors C1 and C2 are
charged up to VCC. The S1 switches are then opened
and the S2 switches are closed so that capacitors C1
and C2 are connected in series between VCC and
VOUT. This performs a voltage tripling function. A pulse-
skipping feedback scheme adjusts the output voltage
to 12V ±5%. The efficiency of the MAX662A with VCC =
5V and IOUT = 30mA is typically 76%. See the
Efficiency vs. Load Current graph in the
Typical
Operating Characteristics.
During one oscillator cycle, energy is transferred from
the charge-pump capacitors to the output filter capaci-
tor and the load. The number of cycles within a given
time frame increases as the load current increases or
as the input supply voltage decreases. In the limiting
case, the charge pumps operate continuously, and the
oscillator frequency is nominally 500kHz.
Shutdown Mode
The MAX662A enters shutdown mode when SHDN is a
logic high. SHDN is a TTL/CMOS-compatible input sig-
nal that is internally pulled up to VCC. In shutdown
mode, the charge-pump switching action is halted and
VIN is connected to VOUT through a 1k
switch. When
entering shutdown, VOUT declines to VCC in typically
13ms. Connect SHDN to ground for normal operation.
When VCC = 5V, it takes typically 400s for the output
to reach 12V after SHDN goes low (Figure 2).
__________Applications Information
Compatibility with MAX662
The MAX662A is a 100%-compatible upgrade of the
MAX662. The MAX662A does not require capacitor C3,
although its presence does not affect performance.
Capacitor Selection
Charge-Pump Capacitors, C1 and C2
The capacitance values of the charge-pump capacitors
C1 and C2 are critical. Use ceramic or tantalum capaci-
tors in the 0.22F to 1.0F range. For applications requir-
ing operation over extended and/or military temperature
ranges, use 1.0F tantalum capacitors for C1 and C2
(Figure 3b).
Input and Output Capacitors, C4 and C5
The type of input bypass capacitor (C4) and output filter
capacitor (C5) affects performance. Tantalums, ceramics
or aluminum electrolytics are suggested. For smallest size,
use Sprague 595D475X9016A7 surface-mount capacitors,
which are 3.51mm x 1.81mm. For lowest ripple, use low-
ESR through-hole ceramic or tantalum capacitors. For low-
est cost, use aluminum electrolytic or tantalum capacitors.
Figure 3a shows the component values for proper opera-
tion over the commercial temperature range using mini-
mum board space. The input bypass capacitor (C4) and
output filter capacitor (C5) should both be at least 4.7F
when using Sprague’s miniature 595D series of tantalum
chip capacitors. Figure 3b shows the suggested compo-
nent values for applications over extended and/or mili-
tary temperature ranges.
The values of C4 and C5 can be reduced to 2F and
1F, respectively, when using ceramic capacitors. If
using aluminum electrolytics, choose capacitance values
of 10F or larger for C4 and C5. Note that as VCC
increases above 5V and the output current decreases,
the amount of ripple at VOUT increases due to the slower
oscillator frequency combined with the higher input volt-
age. Increase the input and output bypass capacitance
to reduce output ripple.
Table 1 lists various capacitor suppliers.
+12V, 30mA Flash Memory
Programming Supply
4
_______________________________________________________________________________________
Figure 2. MAX662A Exiting Shutdown
CIRCUIT OF FIGURE 3, VCC = 5V, IOUT = 200A
5V
0V
12V
5V
SHDN
VOUT
200s/div
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX662ACPA+ | 功能描述:电荷泵 12V 30mA Flash Programming Supply RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 输出电压:- 1.5 V to - 5.5 V, 3 V to 11 V 输出电流:100 mA 电源电流:1 mA 最大工作温度:+ 70 C 封装 / 箱体:SOIC-8 Narrow 封装:Tube |
| MAX662ACSA | 功能描述:电荷泵 12V 30mA Flash Programming Supply RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 输出电压:- 1.5 V to - 5.5 V, 3 V to 11 V 输出电流:100 mA 电源电流:1 mA 最大工作温度:+ 70 C 封装 / 箱体:SOIC-8 Narrow 封装:Tube |
| MAX662ACSA+ | 功能描述:电荷泵 12V 30mA Flash Programming Supply RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 输出电压:- 1.5 V to - 5.5 V, 3 V to 11 V 输出电流:100 mA 电源电流:1 mA 最大工作温度:+ 70 C 封装 / 箱体:SOIC-8 Narrow 封装:Tube |
| MAX662ACSA+T | 功能描述:电荷泵 12V 30mA Flash Programming Supply RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 输出电压:- 1.5 V to - 5.5 V, 3 V to 11 V 输出电流:100 mA 电源电流:1 mA 最大工作温度:+ 70 C 封装 / 箱体:SOIC-8 Narrow 封装:Tube |
| MAX662ACSA+TG068 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
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