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| 型号： | MAX5950ETJ+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 21/28页 |
| 文件大小： | 552K |
| 描述： | IC PWM CTRL HOT-SW 12V 32TQFN-EP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 类型： | 热交换控制器 |
| 应用： | 通用型，PCI Express? |
| 内部开关： | 无 |
| 电源电压： | 8 V ~ 16 V，±5V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-WFQFN 裸露焊盘 |
| 供应商设备封装： | 32-TQFN-EP（5x5） |
| 包装： | 带卷 (TR) |
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12V PWM Controller with Hot-Swap
______________________________________________________________________________________ 21
quency is higher than f
LC
, but lower than the closed-
loop crossover frequency. The equations that define
the error amplifiers poles and zeroes (f
Z1
, f
Z2
, f
P1
, f
P2
,
and f
P3
) are the same as before. However, f
P2
is now
lower than the closed-loop crossover frequency. Figure
7 shows the error-amplifier feedback, as well as its gain
response for circuits that use higher ESR output capac-
itors (tantalum, aluminum electrolytic, etc.)
Pick a value for feedback resistor R5 in Figure 7 (values
between 1k& and 10k& are adequate). C7 is then cal-
culated as:
The circuit is implemented with C7 >> C8 and R3 >>
R6, in which case the error-amplifier gain between f
P2
and f
P3
is approximately equal to:
The modulator gain at f
C
is:
Since G
EA(fC)
x G
MOD(fC)
= 1, R6 can then be calculat-
ed as:
f
P2
is set to f
ZESR
. C6 is then calculated as:
R3 is then calculated as:
f
P3
is set at 5xf
C
. Therefore, C8 is calculated as:
Hot-Swap Controller
Applications Information
Additional External Gate Capacitance
External capacitance can be added from the gate of the
external MOSFET to AGND to reduce the dv/dt of the
PWM controller input voltage (V
PWM_IN
), decreasing the
hot-swap inrush current. Add a 10k& resistor in series
with the added gate capacitor to prevent degrading the
device turn-off response to a fault condition.
Layout Considerations
To take advantage of the switch response time to an
output fault condition, it is important to keep all traces as
short as possible and to maximize the high-current trace
width to reduce the effect of undesirable parasitic
inductance. Use a ground plane to minimize impedance
and inductance. Minimize the trace length that connects
to IN and HSENSE (< 10mm), and ensures accurate
current sensing with Kelvin connections.
When the output is short circuited, the voltage drop
across the external MOSFET becomes large. Hence,
the power dissipation in the switch increases, as does
the die temperature. An efficient way to achieve good
power dissipation on a surface-mount package is to lay
out two copper pads directly under the MOSFET pack-
age on both sides of the board. Connect the two pads
to the ground plane through vias, and use enlarged
copper mounting pads on the top side of the board.
PWM Controller
Applications Information
Power Dissipation
The 32-pin TQFN thermally enhanced package can dis-
sipate 2.7W. Calculate power dissipation in the
MAX5950 as a product of the input voltage and the
total REG output current (I
REG
). I
REG
includes quies-
cent current (I
Q
) and gate-drive current (I
DREG
):
P
D
= V
IN
x I
REG
I
REG
= I
Q
+ [f
SW
x (Q
G1
+ Q
G2
)]
where Q
G1
and Q
G2
represent the total gate charge of
the low-side and high-side external MOSFETs, f
SW
is the
switching frequency of the converter, and I
Q
is the quies-
cent current of the device at the switching frequency.
Use the following equation to calculate the maximum
power dissipation (P
DMAX
) in the chip at a given ambi-
ent temperature (T
A
):
P
DMAX
= 34.5 x (150 - T
A
)&&&.mW
C
R
f
C
8
1
2
5 5
=
?nbsp ?nbsp ?/DIV>
?/DIV>
R
f
C
LC
3
1
2
6
H
?nbsp ?/DIV>
?/DIV>
C
ESR
R
OUT
6
6
=
?/DIV>
R
R G
L C
f
MOD DC
OUT
C
6
5
2
2
2
H
?/DIV>
?nbsp ?/DIV>
?/DIV>
( )
( )
?/DIV>
G
G
L C
f
MOD fC
MOD DC
OUT C
( )
( )
( )
=
?nbsp ?/DIV>
?/DIV>
2
2
2
?/DIV>
R
R
5
f
R
LC
7
1
2 0 5
5
=
?nbsp ?nbsp ?/DIV>
?nbsp .
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX5950EVKIT | 制造商:Maxim Integrated Products 功能描述:12V PWM CONTROLLER WITH HOT-SWAP - Rail/Tube |
| MAX5951ETJ | 功能描述:电压模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX5951ETJ+ | 功能描述:电压模式 PWM 控制器 12V/5V Buck PWM Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX5951ETJ+T | 功能描述:电压模式 PWM 控制器 12V/5V Buck PWM Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX5951ETJ-T | 功能描述:电压模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
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