参数资料
| 型号： | LT1033CT |
| 厂商： | Linear Technology |
| 文件页数： | 5/12页 |
| 文件大小： | 0K |
| 描述： | IC REG LDO NEG ADJ TO220-3 |
| 标准包装： | 50 |
| 稳压器拓扑结构： | 负，可调式 |
| 输出电压： | -1.2 V ~ -32 V |
| 稳压器数量： | 1 |
| 电流 - 限制（最小）： | 3A |
| 工作温度： | 0°C ~ 125°C |
| 安装类型： | 通孔 |
| 封装/外壳： | TO-220-3 |
| 供应商设备封装： | TO-220-3 |
| 包装： | 管件 |
LT1033
APPLICATIO N S I N FOR M ATIO N
? + I ADJ ( R 2 )
V OUT = V REF ? 1 +
R 2 =
– I ADJ
Output Voltage
The output voltage is determined by two external resis-
tors, R1 and R2 (see Figure 1). The exact formula for the
output voltage is:
? R 2 ?
? R 1 ?
Where: V REF = Reference Voltage, I ADJ = Adjustment Pin
Current. In most applications, the second term is small
enough to be ignored, typically about 0.5% of V OUT . In
more critical applications, the exact formula should be
used, with I ADJ equal to 65 μ A. Solving for R2 yields:
V OUT – V REF
V REF
R 1
Smaller values of R1 and R2 will reduce the influence of
I ADJ on the output voltage, but the no-load current drain on
the regulator will be increased. Typical values for R1 are
between 100 ? and 300 ? , giving 12.5mA and 4.2mA
no-load current respectively. There is an additional con-
sideration in selecting R1, the minimum load current
specification of the regulator. The operating current of the
LT1033 flows from input to output. If this current is not
absorbed by the load, the output of the regulator will rise
above the regulated value. The current drawn by R1 and R2
is normally high enough to absorb the current, but care
must be taken in no-load situations where R1 and R2 have
high values. The maximum value for the operating current,
which must be absorbed, is 5mA for the LT1033. If input-
output voltage differential is less than 10V, the operating
current that must be absorbed drops to 3mA.
Capacitors and Protection Diodes
An output capacitor, C3, is required to provide proper
frequency compensation of the regulator feedback loop.
A 2 μ F or larger solid tantalum capacitor is generally
sufficient for this purpose if the 1MHz impedance of the
capacitor is 1 ? or less. High Q capacitors, such as Mylar,
are not recommended because their extremely low ESR
(effective series resistance) can drastically reduce phase
margin. When these types of capacitors must be used
because of other considerations, add a 0.5 ? carbon
resistor in series with 1 μ F. Aluminum electrolytic capaci-
tors may be used, but the minimum value should be 25 μ F
to ensure a low impedance at 1MHz. The output capacitor
should be located within a few inches of the regulator to
keep lead impedance to a minimum. The following caution
should be noted: if the output voltage is greater than 6V
and an output capacitor greater than 20 μ F has been used,
it is possible to damage the regulator if the input voltage
becomes shorted, due to the output capacitor discharging
into the regulator. This can be prevented by using diode D1
(see Figure 2) between the input and the output.
The input capacitor, C2, is only required if the regulator is
more than 4 inches from the raw supply filter capacitor.
Bypassing the Adjustment Pin
The adjustment pin of the LT1033 may be bypassed with
+
C2
5 μ F
+
ADJ
C1
10 μ F
I ADJ
V REF
R2
R1
+
C3
2 μ F
a capacitor to ground, C1, to reduce output ripple, noise,
and impedance. These parameters scale directly with
output voltage if the adjustment pin is not bypassed. A
bypass capacitor reduces ripple, noise and impedance to
that of a 1.25V regulator. In a 15V regulator for example,
–V IN
V IN
V OUT
–V OUT
these parameters are improved by 15V/1.25V = 12 to 1.
= = 704 ?
V OUT – V REF 10V – 1.25V
– 65 μ A
100 ?
– I ADJ
LT1033
LT1033 ? F01
EXAMPLE:
1. A PRECISION 10V REGULATOR TO SUPPLY UP TO 3A LOAD CURRENT.
A. SELECT R1 = 100 ? TO MINIMIZE EFFECT OF I ADJ
B. CALCULATE R2 =
V REF 1.25V
R1
This improvement holds only for those frequencies where
the impedance of the bypass capacitor is less than R1. Ten
microfarads is generally sufficient for 60Hz power line
applications where the ripple frequency is 120Hz, since
X C = 130 ? . The capacitor should have a voltage rating at
least as high as the output voltage of the regulator. Values
Figure 1
1033fc
5
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相关代理商/技术参数 |
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| LT1033CT#PBF | 功能描述:IC REG LDO NEG ADJ TO220-3 RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 标准包装:800 系列:- 稳压器拓扑结构:正，固定式 输出电压:2.5V 输入电压:最高 16V 电压 - 压降（标准）:0.7V @ 4A 稳压器数量:1 电流 - 输出:4A 电流 - 限制（最小）:4.2A 工作温度:0°C ~ 125°C 安装类型:表面贴装 封装/外壳:TO-263-6，D²Pak（5 引线+接片），TO-263BA 供应商设备封装:TO-263-5 包装:带卷 (TR) 其它名称:AP1184K525L-13AP1184K525LDITR |
| LT1033MK | 制造商:Linear Technology 功能描述:Standard Regulator Neg -1.2V to -32V 3A 3-Pin(2+Tab) TO-3 |
| LT1033MK/883 | 制造商:Linear Technology 功能描述:Standard Regulator Neg -1.2V to -32V 3A 3-Pin(2+Tab) TO-3 |
| LT1034BCZ-1.2 | 功能描述:IC VREF SHUNT PREC DUAL TO-92-3 RoHS:否 类别:集成电路 (IC) >> PMIC - 电压基准 系列:- 产品培训模块:Voltage Reference Basics 标准包装:100 系列:- 基准类型:旁路，精度 输出电压:4.096V 容差:±0.075% 温度系数:50ppm/°C 输入电压:- 通道数:1 电流 - 阴极:1µA 电流 - 静态:- 电流 - 输出:10mA 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 供应商设备封装:8-SOIC 包装:管件 |
| LT1034BCZ-1.2#PBF | 功能描述:IC VREF SHUNT PREC DUAL TO-92-3 RoHS:是 类别:集成电路 (IC) >> PMIC - 电压基准 系列:- 产品培训模块:Voltage Reference Basics 标准包装:100 系列:- 基准类型:旁路，精度 输出电压:4.096V 容差:±0.075% 温度系数:50ppm/°C 输入电压:- 通道数:1 电流 - 阴极:1µA 电流 - 静态:- 电流 - 输出:10mA 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 供应商设备封装:8-SOIC 包装:管件 |
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