参数资料
| 型号： | NCP5322ADW |
| 厂商： | ON Semiconductor |
| 文件页数： | 28/31页 |
| 文件大小： | 0K |
| 描述： | IC CTLR BUCK 2PH DRVR/DAC 28SOIC |
| 产品变化通告： | Product Obsolescence 11/Feb/2009 |
| 标准包装： | 26 |
| 应用： | 控制器，高性能处理器 |
| 输入电压： | 4.5 V ~ 14 V |
| 输出数： | 2 |
| 输出电压： | 3.3V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SOIC（0.295"，7.50mm 宽） |
| 供应商设备封装： | 28-SOIC |
| 包装： | 管件 |
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NCP5322A
IRMS,SYNCH + [(1 * D) @
value. Allow for inductance “swing” at full?load by using
three turns. The input inductor ’s value will be:
Li + 32 @ 33.5 nH N2 + 301 nH
This inductor is available as part number CTX15?14771
from Coiltronics.
(27)
(ILo,MAX2 ) ILo,MAX @ ILo,MIN ) ILo,MIN2) 3]1 2
+ [(1 * 0.13) @ (26.52 ) 26.5 @ 18.5 ) 18.52) 3]1 2
+ 21.1 ARMS
Equation 26 is used to calculate the power dissipation of
5. MOSFET & Heatsink Selection
The IPB05N03L from Infineon is chosen for both the
control and synchronous MOSFET due to its low R DS(on)
the synchronous MOSFET:
PD,SYNCH + (IRMS,SYNCH2 @ RDS(on))
(26)
PD,CONTROL + (IRMS,CNTL2 @ RDS(on))
RFBK1 + D VNO?LOAD IBIASVFB
and low gate?charge requirements. The following
parameters are derived from the IPB05N03L data sheet:
Rds ON = 3.9 m W @ 10 V
Q SWITCH = 25 nC
Q RR = 45 nC
Q OSS = 35 nC
Vf diode = 0.86 V @ 25 A
q JC = 1.0 ° C/W
NCP5322A Parameters:
i G = 1.5 A
V G = 10 V
t_nonoverlap = 65 ns
The RMS value of the current in the control MOSFET is
calculated from Equation 20 and the previously derived
values for D, I LMAX , and I LMIN at the converter’s maximum
output current:
IRMS,CNTL + [D @ (ILo,MAX2 ) ILo,MAX @ ILo,MIN (20)
) ILo,MIN2) 3]1 2
+ 0.36 @ [(26.52 ) 26.5 @ 18.5 ) 18.52) 3]1 2
+ 8.15 ARMS
Equation 19 is used to calculate the power dissipation of
the control MOSFET:
(19)
) (ILo,MAX @ Qswitch Ig @ VIN @ fSW)
) (Qoss 2 @ VIN @ fSW) ) (VIN @ QRR @ fSW)
+ (8.152 ARMS @ 3.9 m W )
) (26.5 A @ 25 nC 1.5 A @ 12 V @ 220 kHz)
) (35 nC 2 @ 12 V @ 220 kHz)
) (12 V @ 45 nC @ 220 kHz)
+ 0.26 W ) 1.17 W ) 0.05 W ) 0.12 W
+ 1.60 W
The RMS value of the current in the synchronous
MOSFET is calculated from Equation 27 and the previously
derived values for D, I Lo,MAX , and I Lo,MIN at the converter’s
maximum output current:
) (Vfdiode @ IO,MAX 2 @ t_nonoverlap @ fSW)
+ (21.12 ARMS @ 3.9 m W )
) (0.86 V @ 45 A 2 @ 65 ns @ 220 kHz)
+ 1.74 W ) 0.28 W + 2.02 W
Equation 28 is used to calculate the heat sink thermal
impedances necessary to maintain less than the specified
maximum junction temperatures at 60 ° C ambient:
q CNTL t (125 * 60 ° C) 1.6 W * 1.0 ° C W + 40 ° C W
q SYNCH t (125 * 60 ° C) 2.02 W * 1.0 ° C W + 31 ° C W
If board area permits, a cost effective heatsink could be
formed by using a TO?263 mounting pad of at least 1.5 in 2
for the upper MOSFET and 2.5 in 2 for the lower MOSFET
on a single?sided, 1 oz. copper PCB. The total required pad
area would be slightly less if the area were divided evenly
between top and bottom layers with multiple thermal vias
joining the two areas. To conserve board space, AAVID
offers clip?on heatsinks for TO?220 thru?hole packages.
Examples of these heatsinks include #577002 (1 ″ × 0.75 ″ ×
0.25 ″ , 33 ° C/W at 2 W) and #591302 (0.75 ″ × 0.5 ″ × 0.5 ″ ,
29 ° C/W at 2 W).
6. Adaptive Voltage Positioning
First, to achieve the 220 kHz switching frequency, use
Figure 4 to determine that a 65 k W resistor is needed for
R OSC . Then, use Figure 5 to find the V FB bias current at the
corresponding value of R OSC . In this example, the 65 k W
R OSC resistor results in a V FB bias current of approximately
5.0 m A. Knowing the V FB bias current, one can calculate the
required values for R FBK1 and R DRP using Equations 29
through 31.
The no?load position is easily set using Equation 29:
(29)
+ +30 mV 5.0 m A
+ 6.04 k W
For inductive current sensing, the designer must calculate
the inductor ’s resistance (R L ) and approximate any
resistance added by the circuit board (R PCB ). We found the
http://onsemi.com
28
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| NCP5322ADWG | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:Two−Phase Buck Controller with Integrated Gate Drivers and 5−Bit DAC |
| NCP5322ADWR2 | 功能描述:DC/DC 开关控制器 2 Phase Buck w/Gate RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
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