- 您现在的位置：买卖IC网 > PDF目录19917 > LTC4251-2IS6#TRM (Linear Technology)IC CTRLR HOTSWP NEG VOLT SOT23-6 PDF资料下载
参数资料
| 型号： | LTC4251-2IS6#TRM |
| 厂商： | Linear Technology |
| 文件页数： | 14/24页 |
| 文件大小： | 266K |
| 描述： | IC CTRLR HOTSWP NEG VOLT SOT23-6 |
| 标准包装： | 500 |
| 类型： | 热交换控制器 |
| 应用： | 通用 |
| 内部开关： | 无 |
| 电源电压： | -43V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | SOT-23-6 细型，TSOT-23-6 |
| 供应商设备封装： | SOT-23-6 |
| 包装： | 带卷 (TR) |
| 其它名称： | LTC4251-2IS6 LTC4251-2IS6-ND |
14
425112fd
LTC4251/LTC4251-1/
LTC4251-2
For more information www.linear.com/4251
MOSFET selection is a three-step process. First, R
S
is
calculated, and then the time required to charge the load
capacitance is determined. This timing, along with the
maximum short-circuit current and maximum input volt-
age defines an operating point that is checked against the
MOSFETs SOA curve.
To begin a design, first specify the required load current
and load capacitance, I
L
and C
L
. The circuit breaker current
trip point (50mV/R
S
) should be set to accommodate the
maximum load current. Note that maximum input current
to a DC/DC converter is expected at V
SUPPLY (MIN)
. R
S
is
given by:
R
S
=
40mV
I
L(MAX)
(3)
where 40mV represents the guaranteed minimum circuit
breaker threshold.
During the initial charging process, the LTC4251/
LTC4251-1/LTC4251-2 may operate the MOSFET in current
limit, forcing 80mV to 120mV across R
S
. The minimum
inrush current is given by:
I
INRUSH(MIN)
=
80mV
R
S
(4)
Maximum short-circuit current limit is calculated using
maximum V
SENSE
, or:
I
SHORT-CIRCUIT(MAX)
=
120mV
R
S
(5)
The TIMER capacitor C
T
must be selected based on the
slowest expected charging rate; otherwise TIMER might
time out before the load capacitor is fully charged. A value
for C
T
is calculated based on the maximum time it takes
the load capacitor to charge. That time is given by:
t
CL CHARGE
=
C " V
I
=
C
L
" V
SUPPLY(MAX)
I
INRUSH(MIN)
(6)
Substituting Equation (4) for I
INRUSH(MIN)
and equating
(6) with (2) gives:
C
T
=
C
L
" V
SUPPLY (MAX)
"R
S
" 230礎
(4V " 80mV)
(7)
Returning to Equation (2), the TIMER period is calcu-
lated and used in conjunction with V
SUPPLY(MAX)
and
I
SHORT-CIRCUIT(MAX)
to check the SOA curves of a prospec-
tive MOSFET .
As a numerical design example, consider a 30W load,
which requires 1A input current at 36V . If V
SUPPLY(MAX)
=
72V and C
L
= 100礔 , Equation (3) gives R
SENSE
= 40m?
Equation (7) gives C
T
= 207nF . To account for errors in
R
SENSE
, C
T
, TIMER current (230礎) and TIMER threshold
(4V), the calculated value should be multiplied by 1.5,
giving a nearest standard value of C
T
= 330nF .
If a short-circuit occurs, a current of up to 120mV/40m?
= 3A will flow in the MOSFET for 5.7ms as dictated by
C
T
= 330nF in Equation (2). The MOSFET must be selected
based on this criterion. The IRF530S can handle 100V and
3A for 10ms, and is safe to use in this application.
SUMMARY OF DESIGN FLOW
To summarize the design flow, consider the application
shown in Figure 2, which was designed for 50W:
Calculate maximum load current: 50W/36V = 1.4A; allow-
ing 83% converter efficiency, I
IN (MAX)
= 1.7A.
Calculate R
S
: from Equation (3) R
S
= 20m?
Calculate C
T
: from Equation (7) C
T
= 150nF (including
1.5X correction factor).
Calculate TIMER period: from Equation (2) the short-circuit
time-out period is t = 2.6ms.
Calculate maximum short-circuit current: from Equation
(5) maximum short-circuit current could be as high as
120mV/20m?= 6A.
Consult MOSFET SOA curves: the IRF530S can handle
6A at 72V for 5ms, so it is safe to use in this application.
APPLICATIONS INFORMATION
相关PDF资料 |
PDF描述 |
|---|---|
| ACC22DRST-S273 | CONN EDGECARD 44POS DIP .100 SLD |
| RSM36DTKN-S288 | CONN EDGECARD 72POS .156 EXTEND |
| HBC07DRYS | CONN EDGECARD 14POS DIP .100 SLD |
| RSM36DTKH-S288 | CONN EDGECARD 72POS .156 EXTEND |
| RO-2424S | CONV DC/DC 1W SGL 24V OUT SIP4 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4251BCS6#TRMPBF | 功能描述:IC HOT SWAP CONTROLLER 6SOT23 RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 标准包装:50 系列:- 类型:热交换控制器 应用:-48V 远程电力系统，AdvancedTCA ? 系统，高可用性 内部开关:无 电流限制:可调 电源电压:11.5 V ~ 14.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-MSOP 包装:管件 |
| LTC4251BCS6#TRMPBF | 制造商:Linear Technology 功能描述:HOT SWAP CONTROLLER -48V SOT23-6 |
| LTC4251BCS6#TRPBF | 功能描述:IC HOT SWAP CONTROLLER 6SOT23 RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 标准包装:50 系列:- 类型:热交换控制器 应用:-48V 远程电力系统，AdvancedTCA ? 系统，高可用性 内部开关:无 电流限制:可调 电源电压:11.5 V ~ 14.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-MSOP 包装:管件 |
| LTC4251BCS6-1#TRMPBF | 功能描述:IC HOT SWAP CONTROLLER 6SOT23 RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 标准包装:50 系列:- 类型:热交换控制器 应用:-48V 远程电力系统，AdvancedTCA ? 系统，高可用性 内部开关:无 电流限制:可调 电源电压:11.5 V ~ 14.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-MSOP 包装:管件 |
| LTC4251BCS6-1#TRMPBF | 制造商:Linear Technology 功能描述:HOT SWAP CONTROLLER -48V SOT23-6 |
发布紧急采购，3分钟左右您将得到回复。