- 您现在的位置：买卖IC网 > PDF目录1849 > MAX8739ETP+T (Maxim Integrated Products)IC DC/DC CONV W/OPAMP 20TQFN-EP PDF资料下载
参数资料
| 型号： | MAX8739ETP+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 17/19页 |
| 文件大小： | 0K |
| 描述： | IC DC/DC CONV W/OPAMP 20TQFN-EP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 应用： | 转换器，TFT，LCD |
| 输入电压： | 1.8 V ~ 5.5 V |
| 输出数： | 1 |
| 输出电压： | 1.8 V ~ 13 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-WQFN 裸露焊盘 |
| 供应商设备封装： | 20-TQFN-EP（5x5） |
| 包装： | 带卷 (TR) |
TFT, LCD, DC-DC Converter with
Operational Amplifiers
R 1 = R 2 × ? MAIN ? 1 ?
impedance since the step-up regulator often runs directly
from the output of another regulated supply. Typically,
C IN can be reduced below the values used in the Typical
Application Circuit . Ensure a low noise supply at IN by
using adequate C IN . Alternatively, greater voltage varia-
tion can be tolerated on C IN if IN is decoupled from C IN
using an RC lowpass filter (see Figure 1).
Rectifier Diode
The MAX8739’s high switching frequency demands a
high-speed rectifier. Schottky diodes are recommend-
ed for most applications because of their fast recovery
time and low forward voltage. In general, a 3A Schottky
diode complements the internal MOSFET well.
Output-Voltage Selection
The output voltage of the main step-up regulator can be
adjusted by connecting a resistive voltage-divider from
the output (V MAIN ) to AGND with the center tap connect-
ed to FB (see Figure 1). Select R2 in the 10k ? to 50k ?
range. Calculate R1 with the following equation:
? V ?
? V FB ?
where V FB , the step-up regulator’s feedback set point,
is 1.236V. Place R1 and R2 close to the IC.
Loop Compensation
Choose R COMP to set the high-frequency integrator
gain for fast transient response. Choose C COMP to set
the integrator zero to maintain loop stability.
For low-ESR output capacitors, use the following equa-
tions to obtain stable performance and good transient
response:
Applications Information
Power Dissipation
An IC’s maximum power dissipation depends on the
thermal resistance from the die to the ambient environ-
ment and the ambient temperature. The thermal resis-
tance depends on the IC package, PC board copper
area, other thermal mass, and airflow.
The MAX8739, with its exposed backside pad soldered
to 1in 2 of PC board copper, can dissipate about 1.7W
into +70°C still air. More PC board copper, cooler
ambient air, and more airflow increase the possible dis-
sipation, while less copper or warmer air decreases the
IC’s dissipation capability. The major components of
power dissipation are the power dissipated in the step-
up regulator and the power dissipated by the opera-
tional amplifiers.
Step-Up Regulator
The largest portions of power dissipation in the step-up
regulator are the internal MOSFET, inductor, and the
output diode. If the step-up regulator has 90% efficien-
cy, about 3% to 5% of the power is lost in the internal
MOSFET, about 3% to 4% in the inductor, and about
1% in the output diode. The remaining 1% to 3% is dis-
tributed among the input and output capacitors and the
PC board traces. If the input power is about 5W, the
power lost in the internal MOSFET is about 150mW to
250mW.
Operational Amplifier
The power dissipated in the operational amplifiers
depends on their output current, the output voltage,
and the supply voltage:
PD SOURCE = I OUT_SOURCE x (V SUP - V OUT_ )
R COMP ≈
C COMP ≈
315 × V IN × V OUT × C OUT
L × I MAIN ( MAX )
V OUT × C OUT
10 × I MAIN ( MAX ) × R COMP
PD SINK = I OUT_(SINK) x V OUT_
where I OUT_(SOURCE) is the output current sourced by
the operational amplifier, and I OUT_(SINK) is the output
current that the operational amplifier sinks.
In a typical case where the supply voltage is 10V and
the output voltage is 5V with an output source current
To further optimize transient response, vary R COMP in
20% steps and C COMP in 50% steps while observing
transient response waveforms.
of 30mA, the power dissipated is 150mW.
______________________________________________________________________________________
17
相关PDF资料 |
PDF描述 |
|---|---|
| MAX8740ETB+T | IC CONV DC-DC TFT-LCD 10-TDFN |
| MAX8742EAI+ | IC CNTRLR PWR SUP 28-SSOP |
| MAX8744AETJ+T | IC CNTRLR PWR SUP QUAD 32TQFN |
| MAX8745ETJ+ | IC CNTRLR PWR SUP QUAD 32TQFN |
| MAX8751ETJ+T | IC CNTRLR CCFL INV 32-TQFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8739EVKIT | 功能描述:电源管理IC开发工具 MAX8739 Eval Kit RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| MAX873ACPA+ | 制造商:Maxim Integrated Products 功能描述:V-REF PRECISION 2.5V 10MA 8PDIP N - Rail/Tube |
| MAX873ACSA | 制造商:Maxim Integrated Products 功能描述: |
| MAX873ACSA-T | 制造商:Maxim Integrated Products 功能描述:8 PINS N.SO PKG - Tape and Reel |
| MAX873ACSA-TG068 | 制造商:Maxim Integrated Products 功能描述:8 PINS N.SO PKG - Bulk |
发布紧急采购，3分钟左右您将得到回复。