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NB675 参数 Datasheet PDF下载

NB675图片预览
型号: NB675
PDF下载: 下载PDF文件 查看货源
内容描述: 24V高电流同步降压转换器1.5A LDO和磨光参考 [24V, High Current Synchronous Buck Converter With 1.5A LDO and Buffed Reference]
分类和应用: 转换器
文件页数/大小: 21 页 / 617 K
品牌: MPS [ MONOLITHIC POWER SYSTEMS ]
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NB675 –24V, HIGH CURRENT SYNCHRONOUS BUCK CONVERTER  
PIN FUNCTIONS  
PIN #  
Name  
Description  
Bootstrap. A capacitor connected between SW and BST pins is required to form a  
floating supply across the high-side switch driver.  
1
BST  
Switch Output. Connect this pin to the inductor and bootstrap capacitor. This pin is  
driven up to the VIN voltage by the high-side switch during the on-time of the PWM  
duty cycle. The inductor current drives the SW pin negative during the off-time. The on-  
resistance of the low-side switch and the internal diode fixes the negative voltage. Use  
wide and short PCB traces to make the connection. Try to minimize the area of the SW  
pattern.  
2, 3  
SW  
Buffered VTT reference output. Decouple with a minimum 0.22μF ceramic capacitor as  
4
VTTREF close to the pin as possible. X7R or X5R grade dielectric ceramic capacitors are  
recommended for their stable temperature characteristics.  
Buck regulator output voltage sense. Connect this pin to the output capacitor of the  
regulator directly  
5
6
VDDQSEN  
VINLDO  
VTT  
VTT LDO regulator input. Connect VINLDO to VDDQ in typical application.  
VTT LDO output. Decouple with a minimum 10uF ceramic capacitor as close to the pin  
as possible. X7R or X5R grade dielectric ceramic capacitors are recommended for their  
stable temperature characteristics.  
7
Analog ground. The internal reference is referred to AGND. Connect the GND of the  
FB divider resistor to AGND for better load regulation.  
8
9
AGND  
VTTSEN VTT output sense. Connect this pin to the output capacitor of the VTT regulator directly  
10,11  
Exposed  
Pad 20,21  
PGND  
VIN  
Power Ground. Use wide PCB traces and multiple vias to make the connection.  
12  
Exposed  
Pad 19  
Supply Voltage. The VIN pin supplies power for internal MOSFET and regulator. The  
NB675 operate from a +5V to +22V input rail. An input capacitor is needed to decouple  
the input rail. Use wide PCB traces and multiple vias to make the connection.  
Power good output, the output of this pin is an open drain signal and is high if the  
output voltage is higher than 95% of the nominal voltage. There is a delay from FB ≥  
95% to PG goes high.  
13  
PG  
Feedback. An external resistor divider from the output to GND, tapped to the FB pin,  
sets the output voltage. Place the resistor divider as close to FB pin as possible. Avoid  
vias on the FB traces. It is recommend to set the current through FB resistors around  
10uA.  
14  
FB  
Enable. EN1 and EN2 are digital inputs, which are used to enable or disable the  
internal regulators. Once EN1=EN2=1, the VDDQ regulator, VTT LDO and VTTREF  
output will be turned on; when EN1=0 and EN2=1, the VDDQ regulator and VTTREF  
are active while VTT LDO is off; all the regulators will be turned off when EN1=EN2=0.  
15  
16  
EN1  
VCC  
Internal 5V LDO output. The driver and control circuits are powered from this voltage.  
Decouple with a minimum 1µF ceramic capacitor as close to the pin as possible. X7R  
or X5R grade dielectric ceramic capacitors are recommended for their stable  
temperature characteristics.  
Enable. EN1 and EN2 are digital inputs, which are used to enable or disable the  
internal regulators. Once EN1=EN2=1, the VDDQ regulator, VTT LDO and VTTREF  
output will be turned on; when EN1=0 and EN2=1, the VDDQ regulator and VTTREF  
are active while VTT LDO is off; all the regulators will be turned off when EN1=EN2=0.  
17  
18  
EN2  
NC  
Not connected.  
NB675 Rev. 1.0  
1/14/2013  
www.MonolithicPower.com  
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.  
© 2013 MPS. All Rights Reserved.  
5
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