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| 型号： | MAX1673ESA |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 7/8页 |
| 文件大小： | 0K |
| 描述： | IC REG SWITCHD CAP INV ADJ 8SOIC |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 100 |
| 类型： | 切换式电容器（充电泵），反相 |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | -1.5 V ~ -5.5 V |
| 输入电压： | 2 V ~ 5.5 V |
| 频率 - 开关： | 350kHz |
| 电流 - 输出： | 125mA |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 8-SOIC |
| 其它名称： | Q1155209A |
Regulated, 125mA-Output,
Charge-Pump DC-DC Inverter
Linear Mode (Constant-Frequency Mode)
V OUT = -V REF x R2
In LIN mode (LIN/ SKIP = IN), the charge pump runs con-
tinuously at 350kHz. The MAX1673 controls the charge
on C FLY by varying the gate drive on S1 (Figure 2).
When the output voltage falls, C FLY charges faster due
to increased gate drive. Since the device switches con-
tinuously, the regulation scheme minimizes output ripple,
INPUT
5.0V
ON
C IN
10 μ F
OFF
4
SHDN
IN
8
FB
R1
100k
6
V REF
5V
R1
the output noise contains well-defined frequency compo-
nents, and the circuit requires much smaller external
capacitors than in Skip mode for a given output ripple.*
However, LIN mode is less efficient than Skip mode due
to higher operating current (8mA typical).
LIN
C FLY
2.2 μ F
SKIP
2
3
1
CAP+ MAX1673
CAP-
LIN/SKIP
OUT
GND
R2
60.4k
5
C OUT
22 μ F
OUTPUT
-3V
Skip Mode
In Skip mode (LIN/ SKIP = GND), the device switches
only as needed to maintain regulation on FB. Switching
cycles are skipped until the voltage on FB rises above
GND. Skip mode has higher output noise than LIN
mode, but minimizes operating current.
Shutdown Mode
When SHDN (a CMOS-compatible input) is driven low,
the MAX1673 enters low-power shutdown mode.
Charge-pump switching action halts and an internal 1 ?
switch pulls V OUT to ground. Connect SHDN to IN or
drive high for normal operation.
*See Output Ripple vs. Load Current in Typical Operating Characteristics.
Applications Information
Resistor Selection
(Output Voltage Selection)
The accuracy of V OUT depends on the accuracy of the
voltage biasing the voltage-divider network (R1, R2).
Use a separate reference voltage if V IN is an unregulat-
ed voltage or if greater accuracy is desired (Figure 4).
Adjust the output voltage from -1.5V to -V IN in LIN
mode or 0V to -V IN in Skip mode with external resistors
R1 and R2 as shown in Figures 1 and 4. In either regu-
lating mode (LIN or Skip), FB servos to 0V. Use the
following equations to select R1 and R2 for the desired
output voltage:
7
Figure 4. Separate V REF for Voltage Divider
Capacitor Selection
A C FLY value of 1μF or more is sufficient to supply the
specified load current. However, for minimum ripple in
Skip mode, this value may need to be increased.
Maxim recommends 2.2μF.
Surface-mount ceramic capacitors are preferred for
C FLY , due to their small size, low cost, and low equiva-
lent series resistance (ESR). To ensure proper opera-
tion over the entire temperature range, choose ceramic
capacitors with X7R (or equivalent) low-temperature-
coefficient (tempco) dielectrics. See Table 1 for a list of
suggested capacitor suppliers.
The output capacitor stores the charge transferred from
the flying capacitor and services the load between
oscillator cycles. A good general rule is to make the
output capacitance at least ten times greater than that
of the flying capacitor.
When in Skip mode, output ripple depends mostly on
two parameters: charge transfer between the capaci-
tance values of C FLY and C OUT , and the ESR of C OUT .
The ESR ripple contribution occurs as C OUT charges.
The charging current creates a negative voltage pulse
V OUT = - V REF
R2
R1
across the capacitor ’s ESR that recedes as C OUT
charges. At equilibrium, when the voltage on C FLY
approaches that on C OUT , no charging current flows.
where V REF can be either V IN or some other positive
reference source.
Typically, choose a voltage-divider current of 50μA to
minimize the effect of FB input current:
R1 = V REF / 50μA
R2 = -V OUT / 50μA
Secondly, the ripple contribution due to charge transfer
between capacitors creates a pulse as charge flows to
C OUT . Adding the two terms does not determine peak-
to-peak ripple because their peaks do not occur at the
same time. It is best to use only the dominant term. The
expression for the ripple component predominantly due
to C OUT ESR is:
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相关代理商/技术参数 |
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|---|---|
| MAX1673ESA+ | 功能描述:电荷泵 Regulated 125mA Charge Pump 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 |
| MAX1673ESA+T | 功能描述:电荷泵 Regulated 125mA Charge Pump 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 |
| MAX1673ESA-T | 功能描述:电荷泵 Regulated 125mA Charge Pump 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 |
| MAX1674EUA | 功能描述:直流/直流开关转换器 Compact Step-Up DC/DC Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX1674EUA+ | 功能描述:直流/直流开关转换器 Compact Step-Up DC/DC Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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