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| 型號： | MIC2595-1BM |
| 廠商： | MICREL INC |
| 元件分類： | 電源管理 |
| 英文描述： | Replaced by PTH05060W : |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO14 |
| 封裝： | SOIC-14 |
| 文件頁數(shù)： | 12/17頁 |
| 文件大?。?/td> | 100K |
| 代理商： | MIC2595-1BM |
MIC2589/2595
Micrel
M9999-031504
12
March 2004
Circuit Breaker Function
The MIC2589/89R and the MIC2595/95R employ an elec-
tronic circuit breaker that protects the external power MOSFET
and other system components against large-scale faults,
such as short circuits. The current-limit threshold is set via an
external resistor, R
SENSE
, connected between the V
EE
and
SENSE. For the MIC2589/89R and MIC2595/95R, a timer is
set via capacitor C
FILTER
that determines the length of the
time delay (t
FLT
) for which the device remains in current limit
before the circuit breaker is tripped. This programmable
delay prevents tripping of the circuit breaker because of high
inrush current charging bulk and distributed capacitive loads.
Whenever the voltage across R
SENSE
exceeds 50mV, two
things happen:
1. A constant-current regulation loop is engaged which
is designed to hold the voltage across R
SENSE
equal
to 50mV. This protects both the load and the
MIC2589/95 circuits from excessively high currents.
This current-regulation loop will engage in less than
1
μ
s from the time at which the overvoltage condition
on R
SENSE
occurs.
2. Capacitor C
FILTER
is charged up to an internal
V
CFILTER(TRIP)
threshold (= 1.25V) by an internal
95
μ
A current source. If the voltage across C
FILTER
crosses this threshold, the circuit breaker trips and
the GATE pin is immediately pulled low by an internal
current pull-down. This operation turns off the
MOSFET quickly and disconnects the input from the
load. The value of C
FILTER
should be selected to
allow the circuit
’
s minimum regulated value of I
OUT
to equal I
TRIP
for somewhat longer than the time it
takes to charge the total load capacitance.
An initial value for C
FILTER
is found by calculating the time it
will take for the MIC2589/95 to completely charge up the
output capacitive load. Assuming the load is enabled by the
PWRGD
X
(or /PWRGD
X
) signal(s) of the IC, the turn-on delay
time is derived from the following expression,
I = C
×
(dv/dt):
×
(
t
C
V
–
V
I
TURN-ON
LOAD
DD
EE
LIMIT
=
)
Using parametric values specific to the MIC2589/95, an
expression relating a design nominal value for C
FILTER
to the
circuit
’
s turn-on delay time is:
(
C
(nom)
t
I
(typ)
V
(typ)
t
95 A
1.25V
t
76 10
F
sec
FILTER
TURN-ON
CFILTER
CFILTER
×
TURN-ON
TURN-ON
–
6
=
×
)
=
=
×
μ
Substituting the variables above with the specification limits
of the MIC2589/95, an expression for the worst-case value for
C
FILTER
is given by:
C
(max)
t
135 A
1.17V
t
115.4 10
F
sec
FILTER
TURN-ON
TURN-ON
–
6
=
×
=
×
μ
For example, in a system with a C
LOAD
= 150
μ
F, a maximum
(V
DD
–
V
EE
) = 72V, and a maximum load current on a nominal
–
48V buss of 1.65A, the nominal circuit design equations
steps are:
1. Choose I
LIMIT
= I
HOT_SWAP
(nom) = 2A (1.65A + 20%);
38.8mV
2A
standard value is 19.6m
);
3. Using I
CHARGE
= I
LIMIT
= 2A, the application circuit turn-
on time is calculated:
(
2. Select an
R
19.4m
SENSE
=
=
(closest 1%
t
150 F
72V
2A
5.4ms (use 6 ms)
TURN-ON
=
)
=
Allowing for capacitor tolerances and a nominal 6ms turn-on
time, an initial worst-case value for C
FILTER
is:
C
FILTER(WORST-CASE)
= 6ms x (115.4
×
10
–
6
μ
F/sec) = 692nF
The closest standard
±
5% tolerance capacitor value is 698nF
and would be a good initial starting value for prototyping.
Whenever the hot swap controller is not in current limit, C
FILTER
is discharged to V
EE
by an internal 4
μ
A current source.
For the MIC2589R/95R devices, the circuit breaker automati-
cally resets after (20) t
FLT
time constants (20
×
t
FLT
). If the fault
condition still exists, capacitor C
FILTER
will again be charge up
to V
FILTER(TRIP)
where the circuit breaker is tripped. Capacitor
C
FILTER
will then be discharged by an internal 4
μ
A current
source until the voltage across C
FILTER
goes below
V
FILTER(RETRY)
, at which time another start cycle is initiated.
This will continue until the fault condition is removed or input
power is removed/cycled. The duty cycle of the auto-restart
function is therefore fixed at 5% and the period of the auto-
restart cycle is given by:
t
20
C
1.25V
–
0.22V
95 A
C
216.8ms
F
AUTO-RESTART
FILTER
FILTER
=
×
(
)
×
(
)
=
×
μ
The auto-restart period for the example above where the
worst-case C
FILTER
was determined to be 698nF is:
t
AUTO-RESTART
= 151ms
Current Sensing
As mentioned before, the MIC2589/89R and the MIC2595/95R
use an external, low-value resistor in series with the source
of the external MOSFET to measure the current flowing into
the load. The V
EE
connection (Pin 7) to the IC is one input to
the device
’
s internal current sensing circuits and the SENSE
connection (Pin 9) is the other input.
The sense resistor is nominally valued at:
R
(nom)
V
(typ)
(nom)
I
SENSE
TRIP
HOT_SWAP
=
where V
TRIP
(typ) is the nominal circuit breaker threshold
voltage (= 50mV) and I
HOT_SWAP
(nom) is the nominal hot
swap load current level to trip the internal circuit breaker in the
application.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MIC2595-2BM | Replaced by PTH05060W : |
| MIC2589R-1BM | SINGLE-CHANNEL NEGATIVE HIGH VOLTAGE HOT SWAP POWER CONTROLLERS/SEQUENCERS |
| MIC2753-RBM5 | Power Supply Supervisors Preliminary Information |
| MIC2753-SBM5 | Power Supply Supervisors Preliminary Information |
| MIC2754-LBM5 | Power Supply Supervisors Preliminary Information |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MIC2595-1BM TR | 功能描述:IC CTRLR HOT SWAP NEG HV 14-SOIC 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 |
| MIC2595-1YM | 功能描述:熱插拔功率分布 Negative Voltage Hot-Swap Controller - 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 |
| MIC2595-1YM TR | 功能描述:熱插拔功率分布 Negative Voltage Hot-Swap Controller - 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 |
| MIC2595-1YM-TR | 功能描述:Hot Swap Controller, Sequencer 1 Channel -48V 14-SOIC 制造商:microchip technology 系列:- 包裝:剪切帶（CT） 零件狀態(tài):停產(chǎn) 類型:熱交換控制器，序列發(fā)生器 通道數(shù):1 內(nèi)部開關(guān):無 應(yīng)用:-48V 特性:閉鎖故障 可編程特性:限流，故障超時，UVLO 電壓 - 電源:-80 V ~ -19 V 電流 - 輸出（最大值）:- 工作溫度:-40°C ~ 85°C 電流 - 電源:4mA 安裝類型:表面貼裝 封裝/外殼:14-SOIC（0.154"，3.90mm 寬） 供應(yīng)商器件封裝:14-SOIC 功能引腳:CFILTER，CNLD，DRAIN，PGTIMER，OFF，ON，PWRGD1，PWRGD2，PWRGD3 標(biāo)準(zhǔn)包裝:1 |
| MIC2595-2BM | 功能描述:IC CTRLR HOT SWAP NEG HV 14-SOIC 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 |
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