- 您现在的位置：买卖IC网 > PDF目录44983 > LT1961IMS8E#TR (LINEAR TECHNOLOGY CORP) 3 A SWITCHING REGULATOR, 1500 kHz SWITCHING FREQ-MAX, PDSO8 PDF资料下载
参数资料
| 型号： | LT1961IMS8E#TR |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 3 A SWITCHING REGULATOR, 1500 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封装： | PLASTIC, MSOP-8 |
| 文件页数： | 4/16页 |
| 文件大小： | 154K |
| 代理商： | LT1961IMS8E#TR |
12
LT1961
1961fa
APPLICATIONS INFORMATION
WU
U
THERMAL CALCULATIONS
Power dissipation in the LT1961 chip comes from four
sources: switch DC loss, switch AC loss, drive current, and
input quiescent current. The following formulas show how
to calculate each of these losses. These formulas assume
continuous mode operation, so they should not be used
for calculating efficiency at light load currents.
DC duty cycle
VV
V
I
VI
V
OUT
IN
OUT
SW
OUT
IN
,
()
()(
)
=
=
Switch loss:
PDC I
R
n I
V
f
SW
OUT
=+
()( )( )
()(
) (
)
2
17
VIN loss:
P
VI
DC
mA V
VIN
IN
SW
IN
=+
()(
)(
)
()
50
1
RSW = Switch resistance (≈ 0.27Ω hot)
Example: VIN = 5V, VOUT = 12V and IOUT = 0.5A
Total power dissipation = 0.23 + 0.31 + 0.07 + 0.005 =
0.62W
Thermal resistance for LT1961 package is influenced by
the presence of internal or backside planes. With a full
plane under the package, thermal resistance will be about
50
°C/W. To calculate die temperature, use the appropriate
thermal resistance number and add in worst-case ambient
temperature:
TJ = TA + θJA (PTOT)
If a true die temperature is required, a measurement of the
SYNC to GND pin resistance can be used. The SYNC pin
resistance across temperature must first be calibrated,
with no device power, in an oven. The same measurement
can then be used in operation to indicate the die tempera-
ture.
FREQUENCY COMPENSATION
Loop frequency compensation is performed on the output
of the error amplifier (VC pin) with a series RC network.
The main pole is formed by the series capacitor and the
output impedance (
≈500kΩ) of the error amplifier. The
pole falls in the range of 2Hz to 20Hz. The series resistor
creates a “zero” at 1kHz to 5kHz, which improves loop
stability and transient response. A second capacitor, typi-
cally one-tenth the size of the main compensation capaci-
tor, is sometimes used to reduce the switching frequency
ripple on the VC pin. VC pin ripple is caused by output
voltage ripple attenuated by the output divider and multi-
plied by the error amplifier. Without the second capacitor,
VC pin ripple is:
VC Pin Ripple =
VRIPPLE = Output ripple (VP–P)
gm = Error amplifier transconductance
(
≈850μmho)
RC = Series resistor on VC pin
VOUT = DC output voltage
1.2(VRIPPLE)(gm)(RC)
(VOUT)
To prevent irregular switching, VC pin ripple should be
kept below 50mVP–P. Worst-case VC pin ripple occurs at
maximum output load current and will also be increased if
poor quality (high ESR) output capacitors are used. The
addition of a 47pF capacitor on the VC pin reduces switch-
ing frequency ripple to only a few millivolts. A low value for
RC will also reduce VC pin ripple, but loop phase margin
may be inadequate.
相关PDF资料 |
PDF描述 |
|---|---|
| LT3092ITS8#PBF | SPECIALTY ANALOG CIRCUIT, PDSO8 |
| LT3092ETS8#TRPBF | SPECIALTY ANALOG CIRCUIT, PDSO8 |
| LT3092EST#PBF | SPECIALTY ANALOG CIRCUIT, PDSO3 |
| LT3092ETS8 | SPECIALTY ANALOG CIRCUIT, PDSO8 |
| LT3092IST#PBF | SPECIALTY ANALOG CIRCUIT, PDSO3 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1961IMS8ETRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.5A, 1.25MHz Step-Up Switching Regulator |
| LT1962 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower Low Dropout Regulators with Shutdown |
| LT1962EMS8 | 功能描述:IC REG LDO ADJ .3A 8-MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 产品培训模块:More Information on LDOs 标准包装:50 系列:- 稳压器拓扑结构:正，固定式 输出电压:3.3V 输入电压:最高 15V 电压 - 压降（标准）:1.1V @ 800mA 稳压器数量:1 电流 - 输出:800mA 电流 - 限制（最小）:800mA 工作温度:0°C ~ 125°C 安装类型:表面贴装 封装/外壳:TO-263-4，D²Pak（3 引线+接片），TO-263AA 供应商设备封装:D2PAK-3 包装:管件 |
| LT1962EMS8#PBF | 功能描述:IC REG LDO ADJ .3A 8-MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 产品培训模块:MIC5365/66 Ultra-small LDO Regulators 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:最高 5.5V 电压 - 压降（标准）:0.155V @ 150mA 稳压器数量:1 电流 - 输出:150mA 电流 - 限制（最小）:200mA 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:4-UDFN 裸露焊盘，4-TMLF? 供应商设备封装:4-TMLF?（1x1） 包装:Digi-Reel® 其它名称:576-3192-6 |
| LT1962EMS8#PBF | 制造商:Linear Technology 功能描述:Linear Voltage Regulator IC 制造商:Linear Technology 功能描述:IC, ADJ LDO REG 1.22V TO 20V 0.3A MSOP-8 |
发布紧急采购，3分钟左右您将得到回复。