- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄380408 > MAX6499 (Maxim Integrated Products, Inc.) 72V, Overvoltage-Protection Switches/Limiter Controllers with an External MOSFET PDF資料下載
參數(shù)資料
| 型號(hào)： | MAX6499 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | 72V, Overvoltage-Protection Switches/Limiter Controllers with an External MOSFET |
| 中文描述： | 72V、過壓保護(hù)開關(guān)/限幅控制器，外置MOSFET |
| 文件頁數(shù)： | 10/16頁 |
| 文件大?。?/td> | 359K |
| 代理商： | MAX6499 |
M
MOSFET Selection
Select external MOSFETs according to the application
current level. The MOSFET’s on-resistance (R
DS(ON)
)
should be chosen low enough to have a minimum volt-
age drop at full load to limit the MOSFET power dissi-
pation. Determine the device power rating to
accommodate an overvoltage fault when operating the
MAX6495/MAX6496/MAX6499 in overvoltage-limit mode.
During normal operation, the external MOSFET dissi-
pates little power. The power dissipated in the MOSFET
during normal operation is:
P = I
LOAD
2
x R
DS(ON)
where P is the power dissipated in the MOSFET, I
LOAD
is the output load current, and R
DS(ON)
is the drain-to-
source resistance of the MOSFET.
Most power dissipation in the MOSFET occurs during a
prolonged overvoltage event when operating the
MAX6495/MAX6496/MAX6499 in voltage-limiter mode.
The power dissipated across the MOSFET is as follows
(see the
Thermal Shutdown in Overvoltage-Limiter
Mode
section):
P = V
DS
x I
LOAD
where V
DS
is the voltage across the MOSFET’s drain
and source.
Thermal Shutdown
The MAX6495–MAX6499 thermal-shutdown feature
turns off GATE if it exceeds the maximum allowable
thermal dissipation. Thermal shutdown also monitors
the PC board temperature of the external n-channel
MOSFET when the devices sit on the same thermal
island. Good thermal contact between the MAX6495–
MAX6499 and the external n-channel MOSFET is essen-
tial for the thermal-shutdown feature to operate effec-
tively. Place the n-channel MOSFET as close to
possible to OUTFB.
When the junction temperature exceeds T
J
= +160°C,
the thermal sensor signals the shutdown logic, turning
off the GATE output and allowing the device to cool.
The thermal sensor turns the GATE on again after the
IC’s junction temperature cools by 20°C. Thermal-over-
load protection is designed to protect the MAX6495–
MAX6499 and the external MOSFET in the event of cur-
rent-limit fault conditions. For continuous operation, do
not exceed the absolute maximum junction-tempera-
ture rating of T
J
= +150°C.
Thermal Shutdown in Overvoltage-Limiter Mode
When operating the MAX6495/MAX6496/MAX6499 in
overvoltage-limit mode for a prolonged period of time, a
thermal shutdown is possible. The thermal shutdown is
dependent on a number of different factors:
The device’s ambient temperature
The output capacitor (C
OUT
)
The output load current (I
OUT
)
The overvoltage threshold limit (V
OV
)
The overvoltage waveform period (t
OV
)
The power dissipated across the package (P
DISS
)
During an initial overvoltage occurrence, the discharge
time (
t
1
) of C
OUT
, caused by I
OUT
and I
GATEPD
. The
discharge time is approximately:
where V
OV
is the overvoltage threshold, I
OUT
is the
load current, and I
GATEPD
is the GATE’s 100mA pull-
down current.
Upon OUT falling below the threshold point, the
MAX6495/MAX6496/MAX6499s’ charge-pump current
must recover and begins recharging the external GATE
voltage. The time needed to recharge GATE from -V
D
to the MOSFET’s gate threshold voltage is:
where C
ISS
is the MOSFET’s input capacitance,
V
GS(TH)
is the MOSFET’s gate threshold voltage, V
D
is
the internal clamp (from OUTFB to GATE) diode’s for-
ward voltage and I
GATE
is the charge-pump current
(100μA typ).
t
C
V
V
I
ISS
GS TH
(
D
GATE
2
+
)
=
t
C
V
I
I
OUT
OV
OUT
GATEPD
1
0 95
+
(
)
=
72V, Overvoltage-Protection Switches/Limiter
Controllers with an External MOSFET
10
______________________________________________________________________________________
t
2
t
1
GATE
OUTFB
t
OV
t
3
Figure 4. MAX6495/MAX6496/MAX6499 Timing
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX6501CMP035 | Low-Cost, +2.7V to +5.5V, Micropower Temperature Switches in SOT23 and TO-220 |
| MAX6501UKN000 | Low-Cost, +2.7V to +5.5V, Micropower Temperature Switches in SOT23 and TO-220 |
| MAX6501UKN000-T | SCREWDRIVER, STEPLESSSCREWDRIVER, STEPLESS; Length:220mm; Length, Handle:120mm; Length, blade:100mm |
| MAX6501UKN005 | SCREWDRIVER, STEPLESSSCREWDRIVER, STEPLESS; Length:310mm; Length, Handle:120mm; Length, blade:190mm |
| MAX6501UKN005-T | SCRAPER, PAINTERS 1"SCRAPER, PAINTERS 1"; Length:25mm; Material:Spring Steel |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX6499ATA/V+ | 制造商:Maxim Integrated Products 功能描述:OVERVOLTAGE-PROTECTION SWITCHES/LIMITER CONTROLLERS - Rail/Tube |
| MAX6499ATA/V+T | 制造商:Maxim Integrated Products 功能描述:72V, OVERVOLTAGE-PROTECTION SWITCHES/LIMITER CONTROLLERS WIT - Tape and Reel |
| MAX6499ATA+ | 制造商:Maxim Integrated Products 功能描述: 制造商:Maxim Integrated Products 功能描述:OVERVOLT PROT CNTRLR 8TDFN EP - Rail/Tube |
| MAX6499ATA+T | 功能描述:電流和電力監(jiān)控器、調(diào)節(jié)器 72V Over V Protect Switch/Limiter RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Current Regulators 電源電壓-最大:48 V 電源電壓-最小:5.5 V 工作溫度范圍:- 40 C to + 150 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:HPSO-8 封裝:Reel |
| MAX649C/D | 功能描述:DC/DC 開關(guān)控制器 5V/3.3V/3V or Adjustable High-Efficiency Low-IQ Step-Down DC-DC Controllers RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。