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參數(shù)資料
| 型號： | MIC2594 |
| 廠商： | Micrel Semiconductor,Inc. |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | Single-Channel, Negative High-Voltage Hot Swap Power Controllers |
| 中文描述： | 單通道，負高壓熱插拔電源控制器 |
| 文件頁數(shù)： | 11/14頁 |
| 文件大?。?/td> | 83K |
| 代理商： | MIC2594 |
December 2003
11
M9999-122303
MIC2588/MIC2594
Micrel
Power-Good (PWRGD or /PWRGD) Output
For the MIC2588-1 and the MIC2594-1, the Power-Good
output signal (PWRGD) will be high impedance when V
DRAIN
drops below V
PGTH
, and will pull down to V
DRAIN
when
V
DRAIN
is above V
PGTH
. For the MIC2588-2 and the
MIC2594-2, /PWRGD will pull down to the potential of the
V
DRAIN
pin when V
DRAIN
drops below V
PGTH
, and will be high
impedance when V
DRAIN
is above V
PGTH
. Hence, the -1 parts
have an active-high PWRGD signal and the -2 parts have an
active-low /PWRGD output. Either PWRGD or /PWRGD may
be used as an enable signal for one or more subsequent
DC/DC converter modules or for other system uses as
desired. When used as an enable signal, the time necessary
for the PWRGD (or /PWRGD) signal to pull-up (when in high
impedance state) will depend upon the load (RC) that is
present on this output.
Circuit Breaker Function
The MIC2588 and the MIC2594 employ an electronic circuit
breaker that protects the MOSFET and other system compo-
nents against faults such as short circuits. The current limit
threshold is set via an external resistor, R
SENSE
, connected
between the V
EE
and SENSE pins. An internal 400
μ
s timer
limits the length of time (t
FLT
) for which the circuit can draw
current in excess of its programmed threshold before the
circuit breaker is tripped. This short delay prevents nuisance
tripping of the circuit breaker due to system transients while
providing rapid protection against large-scale transient faults.
Whenever the voltage across R
SENSE
exceeds 50mV, two
things happen:
1. A constant-current regulation loop is engaged de-
signed to hold the voltage across R
SENSE
equal to
50mV. This protects both the load and the MIC2588
circuit from excessively high currents. This loop will
engage in less than 1
μ
s from the time at which the
overvoltage condition on R
SENSE
occurs.
2. The internal 400
μ
s timer is started. If the 400
μ
s
timeout period is exceeded, 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.
Current Sensing
As mentioned before, the MIC2588 and the MIC2594 employ
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 to the IC from the negative supply
is also one input to the part
’
s internal current sensing circuits
and the SENSE input is the other input.
Sense Resistor Selection
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.
To accommodate worst-case tolerances in the sense resistor
(for a
±
1% initial tolerance, allow
±
3% tolerance for variations
over time and temperature) and circuit breaker threshold
voltages, a slightly more detailed calculation must be used to
determine the minimum and maximum hot swap load
currents.
As the MIC2588/94
’
s minimum current limit threshold voltage
is 40mV, the minimum hot swap load current is determined
where the sense resistor is 3% high:
I
(min)
40mV
1.03 R
(
(nom)
38.8mV
R
(nom)
HOT_SWAP
SENSE
SENSE
=
)
=
Keep in mind that the minimum hot swap load current should
be greater than the application circuit
’
s upper steady-state
load current boundary. Once the lower value of R
SENSE
has
been calculated, it is good practice to check the maximum hot
swap load current (I
HOT_SWAP
(max)) which the circuit may let
pass in the case of tolerance build-up in the opposite direc-
tion. Here, the worst-case maximum is found using a
V
TRIP
(max) of 60mV and a sense resistor, 3% low in value:
60mV
0.97 R
SENSE
In this case, the application circuit must be sturdy enough to
operate over a ~1.6-to-1 range in hot swap load currents. For
example, if an MIC2594 circuit must pass a minimum hot
swap load current of 4A without nuisance trips, R
SENSE
should be set to
38.8mV
4A
standard value is 9.76m
. At the other tolerance extremes,
I
HOT_SWAP
(max) for the circuit in question is then simply
61.9mV
9.76m
With a knowledge of the application circuit
’
s maximum hot
swap load current, the power dissipation rating of the sense
resistor can be determined using P = I
2
×
R. Here, the I is
I
HOT_SWAP
(max) = 6.3A and the R is R
SENSE
(min)
=
(0.97)(R
SENSE
(nom)) = 9.47m
. Thus, the sense resistor
’
s
maximum power dissipation is:
P
MAX
= (6.3A)
2
×
(9.47m
) = 0.376W
A 0.5
sense resistor is a good choice in this application.
Undervoltage/Overvoltage Detection
—
MIC2588
The MIC2588 has
“
UV
”
and
“
OV
”
input pins. These pins can be
used to detect input supply rail undervoltage and overvoltage
conditions. Undervoltage lockout prevents energizing the load
until the supply input is stable and within tolerance. In a similar
fashion, overvoltage turn-off prevents damage to sensitive
circuit components should the input voltage exceed normal
operational limits. Each of these pins is internally connected to
an analog comparator with 20mV of hysteresis. When the UV
pin falls below its V
UVL
threshold or the OV pin is above its V
OVH
threshold, the GATE pin is immediately pulled low. The GATE
pin will be held low until UV exceeds its V
UVH
threshold or OV
drops below its V
OVL
threshold. The UV and OV circuit
’
s
threshold trip points are programmed using the resistor divider
I
(max)
(nom)
61.9mV
R
(nom)
HOT_SWAP
SENSE
=
(
)
=
9.7m
=
, and the nearest 1%
I
(max)
6.3A
HOT_SWAP
=
相關PDF資料 |
PDF描述 |
|---|---|
| MIC2594-1BM | Single-Channel, Negative High-Voltage Hot Swap Power Controllers |
| MIC2594-2BM | Replaced by PTH05060W : |
| MIC2595R-2BM | SINGLE-CHANNEL NEGATIVE HIGH VOLTAGE HOT SWAP POWER CONTROLLERS/SEQUENCERS |
| MIC2595R-1BM | SINGLE-CHANNEL NEGATIVE HIGH VOLTAGE HOT SWAP POWER CONTROLLERS/SEQUENCERS |
| MIC2589 | Replaced by PTH05060W : |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MIC2594-1BM | 功能描述:IC CTRLR HOT SWAP NEG HV 8-SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 產(chǎn)品培訓模塊:Obsolescence Mitigation Program 標準包裝:100 系列:- 類型:熱插拔開關 應用:通用 內(nèi)部開關: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 供應商設備封裝:10-TDFN-EP（3x3） 包裝:管件 |
| MIC2594-1BM TR | 功能描述:IC CTRLR HOT SWAP NEG HV 8-SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 熱交換 系列:- 產(chǎn)品培訓模塊:Obsolescence Mitigation Program 標準包裝:100 系列:- 類型:熱插拔開關 應用:通用 內(nèi)部開關: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 供應商設備封裝:10-TDFN-EP（3x3） 包裝:管件 |
| MIC2594-1YM | 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: 安裝風格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
| MIC2594-1YM 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: 安裝風格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
| MIC2594-1YM-TR | 功能描述:Hot Swap Controller 1 Channel -48V 8-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 通道數(shù):1 內(nèi)部開關:無 應用:-48V 特性:故障超時，閉鎖故障 可編程特性:限流，壓擺率，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:3mA 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應商器件封裝:8-SOIC 功能引腳:DRAIN，OFF，ON，PWRGD 標準包裝:1 |
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