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参数资料
| 型号： | LT3502AEDC |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 1.1 A SWITCHING REGULATOR, 2800 kHz SWITCHING FREQ-MAX, PDSO10 |
| 封装： | 2 X 2 MM, PLASTIC, DFN-10 |
| 文件页数： | 2/20页 |
| 文件大小： | 457K |
| 代理商： | LT3502AEDC |
LT3502/LT3502A
10
3502f
APPLICATIONS INFORMATION
There are several graphs in the Typical Performance
Characteristics section of this data sheet that show the
maximum load current as a function of input voltage and
inductor value for several popular output voltages. Low
inductance may result in discontinuous mode opera-
tion, which is okay, but further reduces maximum load
current. For details of the maximum output current and
discontinuous mode operation, see Linear Technology
Application Note 44.
Catch Diode
A low capacitance 500mA Schottky diode is recommended
for the catch diode, D1. The diode must have a reverse
voltage rating equal to or greater than the maximum input
voltage. The Phillips PMEG4005AEA is a good choice; it
is related for 500mA continuous forward current and a
maximum reverse voltage of 40V.
Input Capacitor
Bypass the input of the LT3502/LT3502A circuit with a 1μF
or higher value ceramic capacitor of X7R or X5R type. Y5V
types have poor performance over temperature and applied
voltage and should not be used. A 1μF ceramic is adequate
to bypass the LT3502/LT3502A and will easily handle the
ripple current. However, if the input power source has
high impedance, or there is signicant inductance due to
long wires or cables, additional bulk capacitance may be
necessary. This can be provided with a low performance
electrolytic capacitor.
Step-down regulators draw current from the input supply
in pulses with very fast rise and fall times. The input ca-
pacitor is required to reduce the resulting voltage ripple at
the LT3502/LT3502A and to force this very high frequency
switching current into a tight local loop, minimizing EMI. A
1μF capacitor is capable of this task, but only if it is placed
close to the LT3502/LT3502A and the catch diode (see the
PCB Layout section). A second precaution regarding the
ceramic input capacitor concerns the maximum input volt-
age rating of the LT3502/LT3502A. A ceramic input capaci-
tor combined with trace or cable inductance forms a high
quality (underdamped) tank circuit. If the LT3502/LT3502A
circuit is plugged into a live supply, the input voltage can
ring to twice its nominal value, possibly exceeding the
LT3502/LT3502A’s voltage rating. This situation is easily
avoided; see the Hot Plugging Safely section.
Output Capacitor
The output capacitor has two essential functions. Along
with the inductor, it lters the square wave generated by
the LT3502/LT3502A to produce the DC output. In this role
it determines the output ripple so low impedance at the
switching frequency is important. The second function is to
store energy in order to satisfy transient loads and stabilize
the LT3502/LT3502A’s control loop. Ceramic capacitors
have very low equivalent series resistance (ESR) and
provide the best ripple performance. A good value is:
C
V
C
V
OUT
=
33
66
for the LT3502A
for tthe LT3502
where COUT is in μF. Use an X5R or X7R type and keep
in mind that a ceramic capacitor biased with VOUT will
have less than its nominal capacitance. This choice will
provide low output ripple and good transient response.
Transient performance can be improved with a high value
capacitor, but a phase lead capacitor across the feedback
resistor, R1, may be required to get the full benet (see
the Compensation section).
For small size, the output capacitor can be chosen
according to:
C
V
OUT
=
25
where COUT is in μF. However, using an output capacitor
this small results in an increased loop crossover frequency
and increased sensitivity to noise.
High performance electrolytic capacitors can be used for
the output capacitor. Low ESR is important, so choose one
that is intended for use in switching regulators. The ESR
should be specied by the supplier and should be 0.1
Ω
or less. Such a capacitor will be larger than a ceramic
capacitor and will have a larger capacitance, because the
capacitor must be large to achieve low ESR. Table 2 lists
several capacitor vendors.
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| LT3502AEDC#PBF | 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Down 3V to 40V 8-Pin DFN EP 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Down 3V to 40V 8-Pin DFN EP Bulk 制造商:Linear Technology 功能描述:BUCK SW REG 0.5A 2.2MHZ 8D 制造商:Linear Technology 功能描述:BUCK, SW REG, 0.5A, 2.2MHZ, 8DFN |
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| LT3502AEDC#TRPBF | 功能描述:IC REG BUCK ADJ 0.5A 8DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 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:带卷 (TR) 供应商设备封装:8-SOIC |
| LT3502AEDC-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.1MHz/2.2MHz, 500mA Step-Down Regulators in 2mm × 2mm DFN and MS10 |
| LT3502AEDCTRMPBF | 制造商:Linear Technology 功能描述:DC-DC Converter Step-Down 3-40V DFN8EP 制造商:Linear Technology 功能描述:750kHz/2.2MHz 500mA Step-Down Reg LT3502 |
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