参数资料
| 型号： | EL7585ILZ-T7 |
| 厂商： | Intersil |
| 文件页数： | 11/19页 |
| 文件大小： | 0K |
| 描述： | IC POWER SUPPLY TFT-LCD 20-QFN |
| 标准包装： | 1,000 |
| 应用： | 转换器，TFT，LCD |
| 输入电压： | 3 V ~ 5 V |
| 输出数： | 4 |
| 输出电压： | 5.5 V ~ 20 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-VFQFN 裸露焊盘 |
| 供应商设备封装： | 20-QFN 裸露焊盘（4x4） |
| 包装： | 带卷 (TR) |
EL7585
Operation of the DELB Output Function
An open drain DELB output is provided to allow the boost
as shown in Figure 20. The voltage rating of the external
MOSFET should be greater than V BOOST .
output voltage, developed at C 2 (see application diagram),
to be delayed via an external switch (Q4) to a time after the
V BOOST supply and negative V OFF charge pump supply
have achieved regulation during the start-up sequence
shown in Figure 28. This then allows the A VDD and V ON
supplies to start-up from 0V instead of the normal offset
voltage of V IN -V DIODE (D 1 ) if Q4 were not present.
When DELB is activated by the start-up sequencer, it sinks
50μA allowing a controlled turn-on of Q4 and charge-up of
V IN
EL7585
LX
FB
V BOOST
C 9 . C 16 can be used to control the turn-on time of Q4 to
reduce inrush current into C 9 . The potential divider formed
by R 9 and R 8 can be used to limit the V GS voltage of Q4 if
required by the voltage rating of this device. When the
voltage at DELB falls to less than 0.6V, the sink current is
increased to ~1.2mA to firmly pull DELB to 0V.
The voltage at DELB is monitored by the fault protection
circuit so that if the initial 50μA sink current fails to pull DELB
below ~0.6V after the start-up sequencing has completed,
then a fault condition will be detected and a fault time-out
ramp will be initiated on the C DEL capacitor (C 7 ).
Operation of the PG Output Function
The PG output consists of an internal pull-up PMOS device
to V IN , to turn-off the external Q1 protection switch and a
current limited pull-down NMOS device which sinks ~15μA
allowing a controlled turn-on of Q1 gate capacitance. C O is
used to control how fast Q1 turns-on - limiting inrush current
into C 1 . When the voltage at the PG pin falls to less than
0.6V, the PG sink current is increased to ~1.2mA to firmly
pull the pin to 0V.
The voltage at PG is monitored by the fault protection circuit
so that if the initial 15μA sink current fails to pull PG below
~0.6V after the start-up sequencing has completed, then a
fault condition will be detected and a fault time-out ramp will
be initiated on the C DEL capacitor (C 7 ).
Cascaded MOSFET Application
A 20V N-channel MOSFET is integrated in the boost
regulator. For the applications where the output voltage is
greater than 20V, an external cascaded MOSFET is needed
11
FIGURE 20. CASCADED MOSFET TOPOLOGY FOR HIGH
OUTPUT VOLTAGE APPLICATIONS
Linear-Regulator Controllers (V ON , V LOGIC , and
V OFF )
The EL7585 includes three independent linear-regulator
controllers, in which two are positive output voltage (V ON
and V LOGIC ), and one is negative. The V ON , V OFF , and
V LOGIC linear-regulator controller functional diagrams,
applications circuits are shown in Figures 21, 22, and 23
respectively.
Calculation of the Linear Regulator Base-Emitter
Resistors (R BL , R BP and R BN )
For the pass transistor of the linear regulator, low frequency
gain (Hfe) and unity gain freq. (f T ) are usually specified in the
datasheet. The pass transistor adds a pole to the loop
transfer function at f p =f T /Hfe. Therefore, in order to maintain
phase margin at low frequency, the best choice for a pass
device is often a high frequency low gain switching
transistor. Further improvement can be obtained by adding a
base-emitter resistor R BE (R BP , R BL , R BN in the Functional
Block Diagram), which increase the pole frequency to:
f p =f T *(1+ Hfe *re/R BE )/Hfe, where re=KT/qIc. So choose the
lowest value R BE in the design as long as there is still
enough base current (I B ) to support the maximum output
current (I C ).
We will take as an example the V LOGIC linear regulator. If a
Fairchild FMMT549 PNP transistor is used as the external
pass transistor, Q5 in the application diagram, then for a
maximum V LOGIC operating requirement of 500mA the data
sheet indicates Hfe_min = 100.
FN7345.2
March 9, 2006
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相关代理商/技术参数 |
参数描述 |
|---|---|
| EL7586 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:TFT-LCD Power Supply |
| EL7586_06 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:TFT-LCD Power Supply |
| EL7586A | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:TFT-LCD Power Supply |
| EL7586AILZ | 功能描述:直流/直流开关调节器 EL7586AILZ TFT-LCD PWR SUPY RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| EL7586AILZ-T13 | 功能描述:直流/直流开关调节器 EL7586AILZ TFT-LCD P PWR SUPY RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
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