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| 型号： | LT3021ES8-1.8#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/16页 |
| 文件大小： | 0K |
| 描述： | IC REG LDO 1.8V .5A 8-SOIC |
| 产品培训模块： | More Information on LDOs |
| 标准包装： | 2,500 |
| 稳压器拓扑结构： | 正，固定式 |
| 输出电压： | 1.8V |
| 输入电压： | 最高 10V |
| 电压 - 压降（标准）： | 0.155V @ 500mA |
| 稳压器数量： | 1 |
| 电流 - 输出： | 500mA |
| 电流 - 限制（最小）： | 550mA |
| 工作温度： | -40°C ~ 125°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： | 带卷 (TR) |
LT3021/LT3021-1.2/
LT3021-1.5/LT3021-1.8
APPLICATIONS INFORMATION
The LT3021 is a very low dropout linear regulator capable
of 1V input supply operation. Devices supply 500mA of
output current and dropout voltage is typically 155mV.
Quiescent current is typically 120μA and drops to 3μA in
shutdown. The LT3021 incorporates several protection
features, making it ideal for use in battery-powered sys-
tems. The device protects itself against reverse-input and
reverse-output voltages. In battery backup applications
where the output is held up by a backup battery when the
input is pulled to ground, the LT3021 acts as if a diode is
in series with its output which prevents reverse current
?ow. In dual supply applications where the regulator
load is returned to a negative supply, the output can be
pulled below ground by as much as 10V without affecting
start-up or normal operation.
Adjustable Operation
The LT3021’s output voltage range is 0.2V to 9.5V. Figure
1 shows that the output voltage is set by the ratio of two
external resistors. The device regulates the output to main-
tain the ADJ pin voltage at 200mV referenced to ground.
The current in R1 equals 200mV/R1 and the current in R2
is the current in R1 minus the ADJ pin bias current. The
ADJ pin bias current of 20nA ?ows out of the pin. Use
the formula in Figure 1 to calculate output voltage. An R1
value of 20k sets the resistor divider current to 10μA. Note
that in shutdown the output is turned off and the divider
current is zero. Curves of ADJ Pin Voltage vs Temperature
and ADJ Pin Bias Current vs Temperature appear in the
Typical Performance Characteristics section.
0.4mV at V ADJ = 200mV. At V OUT = 1.5V, load regulation is:
(1.5V/200mV) ? (0.4mV) = 3mV
Output Capacitance and Transient Response
The LT3021’s design is stable with a wide range of output
capacitors, but is optimized for low ESR ceramic capacitors.
The output capacitor’s ESR affects stability, most notably
with small value capacitors. Use a minimum output ca-
pacitor of 3.3μF with an ESR of 0.2Ω or less to prevent
oscillations. The LT3021 is a low voltage device, and output
load transient response is a function of output capacitance.
Larger values of output capacitance decrease the peak
deviations and provide improved transient response for
larger load current changes. For output capacitor values
greater than 22μF a small feedforward capacitor with a
value of 300pF across the upper divider resistor (R2 in
Figure 1) is required. Under extremely low output current
conditions (I LOAD < 30μA) a low frequency small signal
oscillation (200Hz/8mV P-P at 1.2V output) can occur.
A minimum load of 100μA is recommended to prevent
this instability.
Give extra consideration to the use of ceramic capacitors.
Manufacturers make ceramic capacitors with a variety of
dielectrics, each with a different behavior across tempera-
ture and applied voltage. The most common dielectrics
are Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics
provide high C-V products in a small package at low cost,
but exhibit strong voltage and temperature coef?cients.
The X5R and X7R dielectrics yield highly stable character-
isitics and are more suitable for use as the output capacitor
V IN
IN
LT3021
SHDN
GND
OUT
ADJ
R2
R1
+
V OUT
at fractionally increased cost. The X5R and X7R dielectrics
both exhibit excellent voltage coef?cient characteristics.
The X7R type works over a larger temperature range and
exhibits better temperature stability whereas X5R is less
expensive and is available in higher values. Figures 2 and
( )
V OUT = 200mV 1 + – I ADJ (R2)
3021 F01
R2
R1
V ADJ = 200mV
I ADJ = 20nA AT 25 ° C
OUTPUT RANGE = 0.2V TO 9.5V
Figure 1. Adjustable Operation
Speci?cations for output voltages greater than 200mV
are proportional to the ratio of desired output voltage to
200mV; (V OUT /200mV). For example, load regulation for
an output current change of 1mA to 500mA is typically
3 show voltage coef?cient and temperature coef?cient
comparisons between Y5V and X5R material.
Voltage and temperature coefficients are not the only
sources of problems. Some ceramic capacitors have a
piezoelectric response. A piezoelectric device generates
voltage across its terminals due to mechanical stress,
similar to the way a piezoelectric accelerometer or micro-
phone works. For a ceramic capacitor, the stress can be
induced by vibrations in the system or thermal transients.
The resulting voltages produced can cause appreciable
3021fc
10
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相关代理商/技术参数 |
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| LT3021ES8PBF | 制造商:Linear Technology 功能描述:LDO Regulator Adj. 500mA 0.9-10V SOIC8 |
| LT3021IS8-1.8#PBF | 功能描述:IC REG LDO 1.8V .5A 8-SOIC RoHS:是 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 |
| LT3021IS8-1.8#TRPBF | 功能描述:IC REG LDO 1.8V .5A 8-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 标准包装:1 系列:- 稳压器拓扑结构:正，固定式 输出电压:3V 输入电压:2.3 V ~ 5.5 V 电压 - 压降（标准）:0.035V @ 150mA 稳压器数量:2 电流 - 输出:150mA 电流 - 限制（最小）:300mA 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:6-UFDFN 裸露焊盘，6-TMLF? 供应商设备封装:6-TMLF?（1.6x1.6） 包装:Digi-Reel® 产品目录页面:1104 (CN2011-ZH PDF) 其它名称:576-3018-6 |
| LT3022 | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.5A, Low Noise, Negative Linear Regulator |
| LT3022EDHC | 制造商:LINER 制造商全称:Linear Technology 功能描述:1A, 0.9V to 10V, Very Low Dropout Linear Regulator |
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