参数资料
型号: L5983
厂商: STMICROELECTRONICS
元件分类: 稳压器
英文描述: 1.5 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
封装: 3 X 3 MM, 1.08 MM HEIGHT, LEAD FREE, VFQFPN-8
文件页数: 19/37页
文件大小: 832K
代理商: L5983
Application information
L5983
26/37
Doc ID 13005 Rev 6
5.5
Thermal considerations
The thermal design is important to prevent the thermal shutdown of device if junction
temperature goes above 150 °C. The three different sources of losses within the device are:
a)
conduction losses due to the not negligible RDS(on) of the power switch; these are
equal to:
Equation 26
Where D is the duty cycle of the application and the maximum RDS(on) is 220 mΩ. Note that
the duty cycle is theoretically given by the ratio between VOUT an VIN, but actually it is quite
higher to compensate the losses of the regulator. So the conduction losses increases
compared with the ideal case.
b)
switching losses due to power MOSFET turn ON and OFF; these can be
calculated as:
Equation 27
Where TRISE and TFALL are the overlap times of the voltage across the power switch (VDS)
and the current flowing into it during turn ON and turn OFF phases, as shown in Figure 16.
TSW is the equivalent switching time.
For this device the typical value for the equivalent switching time is 50ns.
c)
Quiescent current losses, calculated as:
Equation 28
where IQ is the quiescent current. (IQ = 2.4 mA)
The junction temperature TJ can be calculated as:
Equation 29
Where TA is the ambient temperature and PTOT is the sum of the power losses just seen.
RthJA is the equivalent thermal resistance junction to ambient of the device; it can be
calculated as the parallel of many paths of heat conduction from the junction to the ambient.
P
ON
R
DS on
()
I
OUT
()
2
D
=
P
SW
V
IN
I
OUT
T
RISE
T
FALL
+
()
2
------------------------------------------- Fsw
V
IN
I
OUT
T
SW
F
SW
==
P
Q
V
IN
I
Q
=
T
J
T
A
Rth
JA
P
TOT
+
=
相关PDF资料
PDF描述
L5983TR 1.5 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
L5986A 3.9 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
L5986ATR 3.9 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
L5986TR 3.9 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
L5986 3.9 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
相关代理商/技术参数
参数描述
L5983_08 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:1.5 A step-down switching regulator
L5983TR 功能描述:直流/直流开关调节器 1.5a Step-Down Switching Reg RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5
L5985 功能描述:直流/直流开关调节器 2A STEP-DOWN SWITCH REGULATOR RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5
L5985_08 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:2 A step-down switching regulator
L5985TR 功能描述:直流/直流开关调节器 2a Step-Down Switching Reg RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5