参数资料
型号: MAX1681ESA
厂商: Maxim Integrated Products
文件页数: 8/12页
文件大小: 0K
描述: IC REG MULTI CONFIG 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),倍增器,反相
输出类型: 可调式
输出数: 1
输出电压: -2 V ~ -5.5 V,4 V ~ 11 V
输入电压: 2 V ~ 5.5 V
频率 - 开关: 500kHz,1MHz
电流 - 输出: 125mA
同步整流器:
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
125mA, Frequency-Selectable,
Switched-Capacitor Voltage Converters
Table 4. Minimum Recommended Capacitances for Maximum Output Current
f OSC (kHz)
V IN = 2V
CAPACITANCE (μF) (C1 = C2)
V IN = 3V V IN = 4V
V IN = 5V
125
250
500
1000
2.5
1.2
0.6
0.3
3.8
1.9
0.9
0.4
5.1
2.5
1.2
0.6
6.4
3.2
1.6
0.8
+V INPUT
1 μ F
FSEL
CAP+
IN
SHDN
FSEL
CAP+
IN
SHDN
MAX1681
1 μ F
MAX1681
1 μ F
GND
LV
V OUT = -V INPUT
GND
LV
CAP-
OUT
CAP-
OUT
V OUT = -2V INPUT
1 μ F
NOTE: USE 4.7 μ F CAPACITORS FOR MAX1680.
Figure 1. Cascading MAX1680/MAX1681s to Increase Output Voltage
1 μ F
Bypass Capacitor
Bypass the input voltage to reduce AC impedance and
to prevent internal switching noise. Bypassing depends
on the source impedance location. The AC ripple cur-
rent is 2 x I OUT for the doubler and the inverter. Use a
large bypass capacitor (equal to C1) if the supply has
high AC impedance.
Cascading Devices
To produce larger negative voltages, cascade two
devices (Figure 1). For two devices, the unloaded out-
put voltage is approximately -2 x V INPUT , but this value
is reduced slightly by the first device’s output resis-
tance multiplied by the second device’s quiescent cur-
rent. The effective output resistance for a cascaded
device is larger than that for an individual device (20 ?
for two devices). Cascading several devices increases
output resistance and reduces efficiency. If a large
negative voltage is required for several stages, an
inductive inverting switching regulator such as the
MAX629 or MAX774 may offer more advantages.
Paralleling Devices
Parallel two or more MAX1680/MAX1681s to reduce
output resistance voltage drop under a given load. With
reduced output resistance, paralleled devices deliver
higher load currents. Figure 2 shows two
MAX1680/MAX1681s connected in parallel. Output
resistance is inversely proportional to the number of
devices.
8
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