参数资料
型号: MAX5939DESA+
厂商: Maxim Integrated
文件页数: 9/18页
文件大小: 386K
描述: IC HOT-SWAP CTRLR -48V 8-SOIC
产品培训模块: Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
标准包装: 100
类型: 热交换控制器
应用: 通用
内部开关:
电源电压: -20 V ~ -80 V
工作温度: -40°C ~ 85°C
安装类型: 表面贴装
封装/外壳: 8-SOIC(0.154",3.90mm 宽)
供应商设备封装: 8-SOIC
包装: 管件
-48V Hot-Swap Controllers with External
R
SENSE
and High Gate Pulldown Current
_______________________________________________________________________________________   9
Board Insertion
Figure 6a shows a typical hot-swap circuit for -48V sys-
tems. When the circuit board first makes contact with
the backplane, the DRAIN to GATE capacitance (C
gd
)
of Q1 pulls up the GATE voltage to roughly IV
EE
x
(C
gd
/C
gd
+ C
gs
)I. The MAX5921/MAX5939 feature an
internal dynamic clamp between GATE and V
EE
to
keep the gate-to-source voltage of Q1 low during hot
insertion preventing Q1 from passing an uncontrolled
current to the load. For most applications, the internal
clamp between GATE and V
EE
of the MAX5921/
MAX5939 eliminates the need for an external gate-to-
source capacitor. The resistor R3 limits the current into
the clamp circuitry during card insertion.
Power-Supply Ramping
The MAX5921/MAX5939 can reside either on the back-
plane or the removable circuit board (Figure 6a). Power
is delivered to the load by placing an external N-chan-
nel MOSFET pass transistor in the power-supply path.
After the circuit board is inserted into the backplane,
and the supply voltage at V
EE
is stable and within the
undervoltage and overvoltage tolerance, the
MAX5921/MAX5939 gradually turn on the external
MOSFET by charging the gate of Q1 with a 45礎 cur-
rent source. Capacitor C2 provides a feedback signal
to accurately limit the inrush current.
The inrush current can be calculated:
I
INRUSH
= I
PU
x C
L
/ C2
where C
L
is the total load capacitance, C3 + C4, and
I
PU
is the gate pullup current.
Figure 6b shows the inrush current waveform. The cur-
rent through C2 controls the GATE voltage. At the end
of the DRAIN ramp, the GATE voltage is charged to its
final value. The GATE-to-SENSE clamp limits the maxi-
mum V
GATE
to 18V.
Board Removal
If the circuit card is removed from the backplane, the volt-
age at the UV falls below the UVLO detect threshold, and
the MAX5921/MAX5939 turn off the external MOSFET.
Current Limit and Electronic Circuit
Breaker
The MAX5921/MAX5939 provide current-limiting and cir-
cuit-breaker features that protect against excessive load
current and short-circuit conditions. The load current is
monitored by sensing the voltage across an external
sense resistor connected between V
EE
and SENSE.
MAX5921
MAX5939
V
EE
OV
UV
SENSE
GATE
DRAIN
PWRGD
V
DD
-48V RTN
-48V RTN
SHORT PIN
V
IN
+
V
IN
-
VICOR
VI-J3D-CY
-48V
GATE IN
C4
100礔
100V
C3
0.1礔
100V
C2
15nF
100V
R3
1k&
5%
R2
10&
5%
Q1
IRF530
R1
0.02&
5%
R4
549k&
1%
R5
6.49k&
1%
R6
10k&
1%
4.7nF
Figure 6a. Inrush Control Circuitry/Typical Application Circuit
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MAX5939DESA+ 功能描述:热插拔功率分布 48V- Hot-Swap 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
MAX5939DESA+T 功能描述:热插拔功率分布 48V- Hot-Swap 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
MAX5939DESA-T 功能描述:热插拔功率分布 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
MAX5939EESA 功能描述:热插拔功率分布 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
MAX5939EESA+ 功能描述:热插拔功率分布 48V- Hot-Swap 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