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| 型号： | MIC2341R-2YTQ |
| 厂商： | Micrel Inc |
| 文件页数： | 18/32页 |
| 文件大小： | 1277K |
| 描述： | IC HOT PLUG CTLR DUAL PCI 48TQFP |
| 标准包装： | 250 |
| 类型： | 热交换控制器 |
| 应用： | 通用型，PCI Express? |
| 内部开关： | 无 |
| 电流限制： | 可调 |
| 电源电压： | 3.3V，12V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 48-TQFP |
| 供应商设备封装： | 48-TQFP（7x7） |
| 包装： | 管件 |
| 产品目录页面： | 1085 (CN2011-ZH PDF) |
| 其它名称： | 576-2987 |
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Micrel, Inc.
MIC2341/2341R
October 2007
18
M9999-102507-A
(408) 944-0800
Functional Description
Hot Swap Insertion
When circuit boards are inserted into systems carrying
live supply voltages ( hot-plugged ), high inrush currents
often result due to the charging of bulk capacitance that
resides across the circuit boards supply pins. This
transient inrush current can cause the systems supply
voltages to temporarily go out of regulation, causing data
loss or system lock-up. In more extreme cases, the
transients occurring during a hot-plug event may cause
permanent damage to connectors or on-board
components.
The MIC2341 addresses these issues by limiting the
inrush currents to the load (PCI Express Board), and
thereby controlling the rate at which the loads circuits
turn-on. In addition to this inrush current control, the
MIC2341 offers input and output voltage supervisory
functions and current limiting to provide robust protection
for both the system and circuit board.
System Interface
The MIC2341 employs a hardware system interface that
includes: ON[A/B], AUXEN[A/B], /CRSW[A/B],
/FAULT_MAIN[A/B], /FAULT_AUX[A/B], /PWRGD[A/B],
/INT, and SYSPWRGD.
Power-On Reset
VSTBY[A/B] are the main power supply for the
MIC2341s internal logic circuits and state machines .
VSTBY[A/B] is required for proper operation of the
MIC2341s internal logic circuitry and must be applied at
all times. A Power-On Reset (POR) cycle is initiated
after VSTBY[A/B] is higher than its V
UVLO(STBY)
threshold
voltage and remains valid at that voltage for at least
80祍. All internal logic flags are cleared after POR. If the
VSTBY[A/B] pin voltages are cycled ON-OFF-ON, a
new power-on-reset cycle is initiated. V
STBY
must be the
first supply input applied followed by the MAIN supply
inputs of 12V
IN
and 3V
IN
. During t
POR
, all outputs remain
off. In most applications, the total POR interval will
consist of the time required to charge the V
STBY
input
(bypass) capacitance to the UVLO threshold plus the
internal t
POR
delay time. The following equation is used
to approximate the total POR interval:
(
)
(祍)
t
10
(A)
I
V
C
t
POR
6
Y)
CHARGE(STB
ULVO(STBY)
STBY(礔)
祍)
POR_TOTAL(
+
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
=
where C
STBY
is the V
STBY
input bulk bypass capacitance
and I
CHARGE(STBY)
is the current supplied by the V
STBY
source to charge the capacitance.
+12VOUT[A/B] and +3VOUT[A/B] Start-Up Cycles
All four of the MIC2341s +12V and +3V gate drive
circuits have been designed to drive the gates of
external power MOSFETs. The +12V gate drive circuits
have been designed to drive P-channel MOSFETs and
the +3V gate drive circuits are intended to drive N-
channel MOSFETs. A list of recommended N- and P-
channel power MOSFETs suited for use with the
MIC2341 and PCI Express applications can be found in
Table 2.
These gate drive circuits have also been designed to
limit inrush current in one of two modes: (1) by
controlling the 12VGATE[A/B] or the 3VGATE[A/B]
voltage slew rates (dV
12GATE[A/B]
/dt or dV
3GATE[A/B]
/dt) or (2)
by actively limiting the inrush current, thereby charging
the corresponding load capacitance in current limit. The
mode that the MIC2341 automatically enters is
dependent upon the magnitude of the inrush current and
the magnitude of the load capacitance at 12VOUT[A/B]
and 3VOUT[A/B].
Mode 1: [12V/3V]GATE[A/B] Slew Rate Control
When a slots MAIN supply voltages (12VOUT[A/B] and
3VOUT[A/B]) are OFF, each of the 12VGATE[A/B] pins
is held at 12VIN[A/B] by an internal pull-up transistor.
Similarly, each 3VGATE[A/B] pin is internally held at
AGND. When the MAIN supply voltages are enabled by
a low-to-high transition on the ON[A/B] input pins (recall
that the /CRSW[A/B] inputs must also be asserted), the
12VGATE[A/B] and the 3VGATE[A/B] pins are each
connected to an internal constant current supply,
typically 25 礎 each. At each 12VGATE[A/B] pin, this
constant current supply is a current sink; at each
3VGATE[A/B] pin, the supply is a current source. For
applications where the inrush current is controlled by the
12VGATE[A/B] voltage rate of change, an expression
for the circuits behavior is given by the following
equation:
ISSP
ISSP
TE)
GATE(12VGA
B]
12VGATE[A/
C
25礎
C
I
dt
dV
=
=
where C
ISSP
= P-channel power MOSFET gate input
capacitance.
For example, a Si4435BDY (a 30-V P-channel power
MOSFET) exhibits an approximate C
ISSP
of 1700pF at
V
DS
= 12V. The 12VGATE[A/B] pin voltage rate-of-
change (slew rate) would be:
ms
V
14.7
1700pF
25礎
C
I
dt
dV
ISSP
K)
GATE(12VSN
B]
12VGATE[A/
=
=
=
The 12VOUT[A/B] inrush current to the load while the
12VGATE[A/B] voltage is ramping is dependent on
C
LOAD(12VOUT[A/B])
and C
ISSP
. An expression for the
12VOUT[A/B] inrush current is given by:
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相关代理商/技术参数 |
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| MIC2341R-2YTQ TR | 功能描述:热插拔功率分布 Dual -Slot PCI Express Hot-Plug Controller RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| MIC2342-2YTQ | 功能描述:热插拔功率分布 Dual -Slot PCI Express Hot-Plug Controller RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| MIC2342-2YTQ TR | 功能描述:热插拔功率分布 Dual -Slot PCI Express Hot-Plug Controller RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| MIC2342R-2YTQ | 功能描述:热插拔功率分布 Dual -Slot PCI Express Hot-Plug Controller RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| MIC2342R-2YTQ TR | 功能描述:热插拔功率分布 Dual -Slot PCI Express Hot-Plug Controller RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
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