Micrel, Inc.
MIC2582/MIC2583
April 2009
13
M9999-043009-C
Functional Description
Hot Swap Insertion
When circuit boards are inserted into live system
backplanes and supply voltages, high inrush currents
can result due to the charging of bulk capacitance that
resides across the supply pins of the circuit board. This
inrush current, although transient in nature, may be high
enough to cause permanent damage to on board
components or may cause the systems supply voltages
to go out of regulation during the transient period which
may result in system failures. The MIC2582 and
MIC2583 act as a controller for external N-Channel
MOSFET devices in which the gate drive is controlled to
provide inrush current limiting and output voltage slew
rate control during hot plug insertions.
Power Supply
VCC is the supply input to the MIC2582/83 controller
with a voltage range of 2.3V to 13.2V. The VCC input
can withstand transient spikes up to 20V. In order to
ensure stability of the supply voltage, a minimum 0.47礔
capacitor   from   VCC   to   ground   is   recommended.
Alternatively, a low pass filter, shown in the typical
application circuit (see Figure 1), can be used to
eliminate high frequency oscillations as well as help
suppress transient spikes.
Also, due to the existence of an undetermined amount of
parasitic inductance in the absence of bulk capacitance
along the supply path, placing a Zener diode at the VCC
of the controller to ground in order to provide external
supply transient protection is strongly recommended for
relatively high current applications (e3A). See Figure 1.
Start-Up Cycle
Supply Contact Delay
During a hot insert of a PC board into a backplane or
when the supply (VCC) is powered up, as the voltage at
the ON pin rises above its threshold (1.24V typical), the
MIC2582/83 first checks that both supply voltages are
above their respective UVLO thresholds. If so, the
device is enabled and an internal 2.5礎(chǔ) current source
begins charging capacitor C
POR
to 0.3V to initiate a start-
up sequence. Once the start-up delay (t
START
) elapses,
the CPOR pin is pulled immediately to ground and a
17礎(chǔ) current source begins charging the GATE output
to drive the external MOSFET that switches V
IN
to V
OUT
.
The programmed contact start-up delay is calculated
using the following equation:
(   )
F
C
x
I
V
C
t
POR
CPOR
START
POR
START
?/DIV>
12
.
0
E
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
=
(1)
Where the start-up delay timer threshold (V
START
) is 0.3V,
and the Power-On Reset timer current (I
CPOR
) is 2.5礎(chǔ).
See Table 2 for some typical supply contact start-up
delays using several standard value capacitors. As the
GATE voltage continues ramping toward its final value
(V
CC
  +   V
GS
)   at   a   defined   slew   rate   (See   Load
Capacitance/Gate   Capacitance   Dominated   Startup
sections), a second CPOR timing cycle begins if:
1)/FAULT is high and 2)CFILTER is low (i.e., not an
overvoltage, undervoltage lockout, or overcurrent state).
This second timing cycle (t
POR
) begins when the voltage
at the FB pin exceeds its threshold (V
FB
). This condition
indicates that the output voltage is valid. See Figure 3 in
the Timing Diagrams. When the power supply is already
present (i.e., not a hot swapping condition) and the
MIC2582/83 device is enabled by applying a logic high
signal at the ON pin, the GATE output begins ramping
immediately as the first CPOR timing cycle is bypassed.
Active current regulation is employed to limit the inrush
current transient response during start-up by regulating
the load current at the programmed current limit value
(See Current Limiting and Dual-Level Circuit Breaker
section). The following equation is used to determine the
nominal current limit value:
SENSE
SENSE
TRIPSLOW
LIM
R
mV
R
V
I
50
=
=
(2)
where V
TRIPSLOW
is the current limit slow trip threshold
found in the electrical table and R
SENSE
is the selected
value that will set the desired current limit. There are two
basic start-up modes for the MIC2582/83: 1) Start-up
dominated   by   load   capacitance   and   2)   start-up
dominated by total gate capacitance. The magnitude of
the inrush current delivered to the load will determine the
dominant mode. If the inrush current is greater than the
programmed current limit (I
LIM
), then load capacitance is
dominant. Otherwise, gate capacitance is dominant. The
expected inrush current may be calculated using the
following equation:
GATE
LOAD
GATE
LOAD
GATE
C
C
x
A
C
C
x
I
INRUSH
?/DIV>
17
=
E
(3)
where I
GATE
is the GATE pin pull-up current, C
LOAD
is the
load   capacitance,   and   C
GATE
  is   the   total   GATE
capacitance (C
ISS
of the external MOSFET and any
external capacitor connected from the MIC2582/83
GATE pin to ground).
Load Capacitance Dominated Start-Up
In this case, the load capacitance (C
LOAD
) is large
enough to cause the inrush current to exceed the
programmed current limit but is less than the fast-trip
threshold (or the fast-trip threshold is disabled, M
option). During start-up under this condition, the load
current is regulated at the programmed current limit
value (I
LIM
) and held constant until the output voltage
rises to its final value. The output slew rate and
equivalent GATE voltage slew rate is computed by the
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參數(shù)描述 |
MIC2583R-MYQS |
功能描述:熱插拔功率分布 Single-Channel Hot-Swap Controller - 200mV Fast-Trip Threshold - Lead Free
RoHS:否 制造商:Texas Instruments 產(chǎn)品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
MIC2583R-MYQS TR |
功能描述:熱插拔功率分布 Single-Channel Hot-Swap Controller - 200mV Fast-Trip Threshold - Lead Free
RoHS:否 制造商:Texas Instruments 產(chǎn)品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
MIC2584-JBTS |
功能描述:IC CTRLR HOT SWAP DUAL 16-TSSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 產(chǎn)品培訓(xùn)模塊:Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:100 系列:- 類型:熱插拔開關(guān) 應(yīng)用:通用 內(nèi)部開關(guān):是 電流限制:可調(diào) 電源電壓:9 V ~ 13.2 V 工作溫度:-40°C ~ 150°C 安裝類型:表面貼裝 封裝/外殼:10-WFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:10-TDFN-EP(3x3) 包裝:管件 |
MIC2584-JBTS TR |
功能描述:IC CTRLR HOT SWAP DUAL 16-TSSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 產(chǎn)品培訓(xùn)模塊:Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:100 系列:- 類型:熱插拔開關(guān) 應(yīng)用:通用 內(nèi)部開關(guān):是 電流限制:可調(diào) 電源電壓:9 V ~ 13.2 V 工作溫度:-40°C ~ 150°C 安裝類型:表面貼裝 封裝/外殼:10-WFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:10-TDFN-EP(3x3) 包裝:管件 |
MIC2584-JYTS |
功能描述:熱插拔功率分布 Dual Channel Hot-Swap Controller - 100mV Threshold - Lead Free
RoHS:否 制造商:Texas Instruments 產(chǎn)品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |