- 您现在的位置：买卖IC网 > PDF目录44991 > LTC3543EDCB (LINEAR TECHNOLOGY CORP) 1.3 A SWITCHING REGULATOR, 2250 kHz SWITCHING FREQ-MAX, PDSO6 PDF资料下载
参数资料
| 型号： | LTC3543EDCB |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 1.3 A SWITCHING REGULATOR, 2250 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封装： | 2 X 3 MM, 0.75 MM HEIGHT, PLASTIC, MO-229, DFN-6 |
| 文件页数： | 4/16页 |
| 文件大小： | 295K |
| 代理商： | LTC3543EDCB |
LTC3543
12
3543f
APPLICATIO S I FOR ATIO
WU
U
1. The VIN quiescent current is due to two components: the
DC bias current as given in the Electrical Characteristics
and the internal main switch and synchronous switch
gate charge currents. The gate charge current results
from switching the gate capacitance of the internal power
MOSFET switches. Each time the gate is switched from
high to low to high again, a packet of charge, dQ, moves
from VIN to ground. The resulting dQ/dt is the current out
of VIN that is typically larger than the DC bias current. In
continuous mode, IGATECHG = f(QT + QB) where QT and
QB are the gate charges of the internal top and bottom
switches. Both the DC bias and gate charge losses are
proportional to VIN and thus their effects will be more
pronounced at higher supply voltages.
2. I2R losses are calculated from the resistances of the
internal switches, RSW, and external inductor RL. In
continuous mode, the average output current owing
through inductor L is “chopped” between the main
switch and the synchronous switch. Thus, the series
resistance looking into the SW pin is a function of both
top and bottom MOSFET RDS(ON) and the duty cycle
(DC) as follows:
RSW = (RDS(ON)TOP DC) + (RDS(ON)BOT (1 – DC))
The RDS(ON) for both the top and bottom MOSFETs can
be obtained from the Typical Performance Characteristics
curves. Thus, to obtain I2R losses, simply add RSW to
RL and multiply the result by the square of the average
output current.
Other losses, including CINandCOUTESRdissipativelosses
and inductor core losses, generally account for less than
2% total additional loss.
Thermal Considerations
In most applications, the LTC3543 does not dissipate much
heat due to its high efciency. But, in applications where the
LTC3543 is running at high ambient temperature with low
supply voltage and high duty cycles, such as in dropout,
the heat dissipated may exceed the maximum junction
temperature of the part. If the junction temperature reaches
approximately 150°C, both power switches will be turned
off and the SW node will become high impedance.
To avoid the LTC3543 from exceeding the maximum junc-
tion temperature, the user will need to do some thermal
analysis. The goal of the thermal analysis is to determine
whether the power dissipated exceeds the maximum
junction temperature of the part. The temperature rise is
given by:
TR = θJA PD
where PD is the power dissipated by the regulator and
θJA is the thermal resistance from the junction of the die
to the temperature.
The junction temperature, TJ, is given by:
TJ = TA + TR
where TA is the ambient temperature.
As an example, consider the LTC3543 in dropout at an
input voltage of 2.7V, an ambient temperature of 80°C, and
a load current of 600mA. From the typical performance
graph of switch resistance, the RDS(ON) of the P-channel
switch at 80°C is approximately 0.41Ω. There, power
dissipated by the part is:
PD = ILOAD2 RDS(ON) = 147.6mW
For the DFN package, the θJA is 64°C/W. Thus, the junction
temperature of the regulator is:
TJ = 80°C + 0.1476 64 = 89.4°C
which is well below the maximum junction temperature of
125°C. Note that at higher supply voltages, the junction
temperature is lower due to reduced switch resistance
(RDS(ON)).
Checking Transient Response
The regulator loop response can be checked by looking
at the load transient response. Switching regulators take
several cycles to respond to a step in load current. When
a load step occurs, VOUT immediately shifts by an amount
equal to (ΔILOAD ESR), where ESR is the effective series
resistance of COUT. ΔILOAD also begins to charge or dis-
charge COUT, which generates a feedback error signal.
The regulator loop then acts to return VOUT to its steady
state value. During this recovery time, VOUT can be moni-
tored for overshoot or ringing that would indicate a stability
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3544BEUD#TR | 0.8 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PQCC16 |
| LTC3544EUD | 0.8 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PQCC16 |
| LTC3547BEDDB | 0.7 A DUAL SWITCHING CONTROLLER, 2700 kHz SWITCHING FREQ-MAX, PDSO8 |
| LTC3549EDCB#TRM | 0.6 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
| LTC3549EDCB#TR | 0.6 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3543EDCB#PBF | 制造商:Linear Technology 功能描述:REG STEP DOWN 0.6A SMD DFN-6 制造商:Linear Technology 功能描述:REG, STEP DOWN, 0.6A, SMD, DFN-6 |
| LTC3543EDCB#TRMPBF | 功能描述:IC REG BUCK SYNC ADJ 0.6A 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 |
| LTC3543EDCB#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 0.6A 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 |
| LTC3544 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA |
| LTC3544B | 制造商:LINER 制造商全称:Linear Technology 功能描述:Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA |
发布紧急采购，3分钟左右您将得到回复。