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APW7098QAE-TRG 参数 Datasheet PDF下载

APW7098QAE-TRG图片预览
型号: APW7098QAE-TRG
PDF下载: 下载PDF文件 查看货源
内容描述: 两相降压PWM控制器集成MOSFET驱动器 [Two- Phase Buck PWM Controller with Integrated MOSFET Drivers]
分类和应用: 驱动器开关控制器
文件页数/大小: 30 页 / 650 K
品牌: ANPEC [ ANPEC ELECTRONICS COROPRATION ]
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APW7098  
Function Description  
Voltage(V)  
VCC Linear Controller  
VCC  
VSS  
The VCC linear-regulator controller is an analog gain  
block with an open-drain n-channel output. It drives an  
external NPN or N-channel MOSFET pass transistor with  
a 1kW (typical) pull-up resistor and senses the feedback  
voltage via VCC pin. The regulator uses a 1mF (minimum)  
ceramic output capacitor and is designed to deliver  
100mA (at 8.5V) for VCC.  
V5VCC  
VPOK  
VFB  
5VCC  
POR  
1.5V  
0.6V  
VSS_VT  
5VCC Linear Regulator  
5VCC is the output terminal of the internal 5V linear  
regulator which regulates a 5V voltage on 5VCC by  
controlling an internal bypass transistor between VCC  
and 5VCC. The linear regulator powers the internal  
control circuitry and is stable with a low-ESR ceramic  
output capacitor. Bypass 5VCC to GND with a ceramic  
capacitor of at least 1mF. Place the capacitor physically  
close to the IC to provide good noise decoupling. The  
linear regulator can also provide output current up to  
20mA for external loads. The linear regulator with current-  
limit protection can protect itself during over-load or short-  
circuit conditions on 5VCC pin.  
Time  
Figure 1. Power Sequence  
When soft-start is initiated, the internal 10mA current  
source starts to charge the capacitor. When the soft-start  
voltage across the soft-start capacitor reaches the en-  
abled threshold about 0.8V (VSS_VT), the internal reference  
starts to rise and follows the soft-start voltage with con-  
verter operating at 150k/300k/400kHz PWM switching  
frequency. When output voltage rises to 87.5% of the  
regulation voltage, the power-ok is enabled. The soft-  
start time (from the moment of enabling the IC to the  
moment when VPOK goes high) can be expressed as the  
following equation:  
The 5VCC linear regulator stops regulating in Over-Tem-  
perature Protection. When the junction temperature is  
cooled by 50oC, the 5VCC linear regulator starts to regu-  
late the output voltage again.  
CSS ´ (VSS_VT + VREF ´ 0.875)  
TSS =  
ISS  
where  
CSS= external soft-start capacitor  
VSS_VT= internal soft-start threshold voltage, is about  
0.8V  
5VCC Power-On-Reset (POR) and REFIN/EN (External  
Reference and Enable Input)  
Figure 1 shows the power sequence. The APW7098  
keeps monitoring the voltage on 5VCC pin to prevent  
wrong logic operations which may occur when 5VCC  
voltage is not high enough for the internal control cir-  
cuitry to operate. The 5VCC POR has a rising thresh-  
old of 4.6V (typical) with 0.58V of hysteresis. After the  
5VCC voltage exceeds its rising Power-On-Reset  
(POR) voltage threshold, the IC starts a start-up pro-  
cess and then ramps up the output voltage to the setting  
of output voltage. The 5VCC POR signal resets the  
fault latch, set by the under-voltage or over-current event,  
when the signal is at a low level.  
VREF= 0.6V or the voltage on the REFIN/EN pin  
ISS= soft-start current=10mA  
During soft-start stage, the under-voltage protection is  
inhibited; however, the over-voltage and over-current pro-  
tection functions are enabled. If the output capacitor has  
residue voltage before start-up, both lower and upper  
MOSFETs are in off-state until the internal soft-start volt-  
age equals to the FB pin voltage. This will ensure the  
output voltage starts from its existing voltage level.  
Reference Voltage Selection and Shutdown Control  
The APW7098 features a reference selection function  
to use either internal 0.6V or external reference voltage.  
During the beginning of soft-start, the voltage on  
Copyright ã ANPEC Electronics Corp.  
17  
www.anpec.com.tw  
Rev. A.6 - Oct., 2009