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参数资料
| 型号： | DS1670S |
| 厂商： | DALLAS SEMICONDUCTOR |
| 元件分类： | Timer or RTC |
| 英文描述： | 0 TIMER(S), REAL TIME CLOCK, PDSO20 |
| 封装： | SOIC-20 |
| 文件页数： | 16/16页 |
| 文件大小： | 312K |
| 代理商： | DS1670S |
Detailed Description
The MAX774/MAX775/MAX776 are negative-output,
inverting power controllers that can be configured to drive
an external P-channel MOSFET. The output voltages are
preset to -5V (MAX774), -12V (MAX775), or -15V
(MAX776). Additionally, all three parts can be set to any
desired output voltage using an external resistor divider.
The MAX774/MAX775/MAX776 have a unique control
scheme (Figure 1) that combines the advantage of
pulse-skipping, pulse-frequency-modulation (PFM)
converters (ultra-low supply current) with the advan-
tage of pulse-width modulation (PWM) converters (high
efficiency with heavy loads). This control scheme
allows the devices to achieve 85% efficiency with loads
from 5mA to 1A.
As with traditional PFM converters, the external
P-channel MOSFET power transistor is turned on when
the voltage comparator senses that the output is below
the reference voltage. However, unlike traditional PFM
converters, switching is controlled by the combination
of a switch current limit (210mV/RSENSE) and
on-time/off-time limits set by one-shots. Once turned
on, the MOSFET stays on until the 16s maximum on-
time limit is reached or the switch current reaches its
limit (as set by the current-sense resistor).
Once off, the switch is typically held off for a minimum of
2.3s. It will stay off until the output drops below the level
determined by VREF and the feedback divider network.
With light loads, the MOSFET switches on for one or
more cycles and then switches off, much like in tradi-
tional PFM converters. To increase light-load efficiency,
MAX774/MAX775/MAX776
-5V/-12V/-15V or Adjustable, High-Efficiency,
Low IQ Inverting DC-to-DC Controllers
_______________________________________________________________________________________
9
N
1.5V
REFERENCE
Q
TRIG
ONE-SHOT
Q
TRIG
ONE-SHOT
CURRENT-
CONTROL CIRCUITS
MODE
COMPARATOR
ERROR
COMPARATOR
CURRENT
COMPARATOR
FROM V+
FROM OUT
0.2V
(FULL CURRENT)
0.1V
(HALF CURRENT)
FROM
V+
MAX774
MAX775
MAX776
REF
V+
SHDN
FB
OUT
CS
EXT
GND
S
R
Q
50mV
Figure 1. Functional Diagram
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相关代理商/技术参数 |
参数描述 |
|---|---|
| DS1670S+ | 功能描述:实时时钟 Portable System Controller RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
| DS1671H | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Dual Clock Driver |
| DS1671J-8 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Dual Clock Driver |
| DS-1671ZJ | 制造商:Hikvision USA 功能描述:4" Indoor Ceiling Embedded Mount |
| DS1672 | 制造商:DALLAS 制造商全称:Dallas Semiconductor 功能描述:Low Voltage Serial Timekeeping Chip |
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