参数资料
| 型号： | NCP5218MNR2G |
| 厂商： | ON Semiconductor |
| 文件页数： | 24/31页 |
| 文件大小： | 0K |
| 描述： | IC DDR PWR CTLR 2IN2 NTBK 22-DFN |
| 产品变化通告： | Product Obsolescence 30/Sept/2009 |
| 标准包装： | 2,500 |
| 应用： | 控制器，DDR |
| 输入电压： | 4.5 V ~ 24 V |
| 输出数： | 2 |
| 输出电压： | 可调 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 22-VFDFN 裸露焊盘 |
| 供应商设备封装： | 22-DFN（6x5） |
| 包装： | 带卷 (TR) |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页当前第24页第25页第26页第27页第28页第29页第30页第31页
NCP5218
0.8 Css
tss [
COUTVTT VTT
tSSVTT [
ICIN(RMS) w 10 A 1.836 V * 1.836 V 2 + 4.2 A
L w
+ 1.39 m H (eq. 44)
440 m F ((100 mV ) 1.836 V)2 ? (1.836 V)2)
7 A ) 0.3 7 A 2
(eq. 45)
IL(rated) + 1.2
10 A )
V DDQ is finished. The C ss will continue to charge up until
it reaches about 2.5 V to 3.0 V.
The soft ? start time t ss can be programmed by the
soft ? start capacitor according to the following equation:
(eq. 40)
Iss
Ceramic capacitors with low tolerance and low
temperature coefficient, such as B, X5R, X7R ceramic
capacitors are recommended to be used as the C SS . Ceramic
capacitors with Y5V temperature characteristic are not
recommended.
Soft ? Start of VTT Active Terminator
The VTT source current limit is used as a constant
current source to charge up the VTT output capacitor
during VTT soft ? start. Besides, the VTT source current
limit is reduced to about 1.0 A for 128 internal clock cycles
to minimize the inrush current during VTT soft ? start.
Therefore, the VTT soft ? start time t SSVTT can be estimated
by the equation:
(eq. 41)
ILIMVTSS
where C OUTVTT is the capacitance of VTT output capacitor
and I LIMVTSS is the VTT soft ? start source current limit.
Boost Supply Diode and Capacitor
An external diode and capacitor are used to generate the
boost voltage for the supply of the high ? side gate driver of
the bulk regulator. Schottky diode with low forward
voltage should be used to ensure higher floating gate drive
voltage can be applied across the gate and the source of the
high ? side MOSFET. A Schottky diode with 30 V reverse
voltage and 0.5 A DC current ratings can be used as the
boost supply diode for most applications. A 0.1 m F to
0.22 m F ceramic capacitor should be sufficient as the boost
capacitor.
VTTI Input Power Supply for VTT and VTTR
Both VTT and VTTR are supplied by VTTI for sourcing
current. VTTI is normally connected to the VDDQ output
for optimum performance. If VTTI is connected to VDDQ,
no bypass capacitor is required to add to VTTI since the
bulk capacitor at VDDQ output is sufficiently large.
Besides, the maximum load current of VDDQ is the sum of
I VDDQ(max) and I VTT(max) when making electrical design
and components selection of the VDDQ buck regulator.
VTTI can also be connected to an external voltage source.
However, extra power dissipation will be generated from
the internal VTT high ? side MOSFET and more
heatsinking is required if the external voltage is higher than
VDDQ. Whereas, the headroom will be limit by the R DS(on)
of the VTT linear regulator high ? side MOSFET, and the
to VTTGND with at least a 10 m F capacitor if external
voltage source is used.
Design Example
A design example of a V DDQ bulk converter with the
following design parameters is shown below:
DDR2 V DDQ bulk converter design parameters:
1. Input voltage range: 7.0 V to 20 V.
2. Nominal V OUT : 1.8 V.
3. Static tolerance: 2% ( " 36 mV).
4. Transient tolerance: " 100 mV.
5. Maximum output current: 10 A
(I VDDQ(max) = 8.0 A, I VTT(max) = 2.0 A).
6. Load transient step: 1.0 A to 8.0 A.
7. Switching frequency: 400 kHz.
8. Bandwidth: 100 kHz.
9. Soft ? start time: 400 m s.
a. Calculate input capacitor rms ripple current rating and
voltage rating:
8.0 V 8.0 V
(eq. 42)
VCIN(rating) w 20 1.25 V + 25 V (eq. 43)
Therefore, two 10 m F 25 V ceramic capacitors with 1210
size in parallel are used.
b. Calculate inductance, rated current and DCR of
inductor:
First, suppose ripple current is 0.3 times the maximum
output current, such that:
(20 V ? 1.836 V) 1.836 V
0.3 10 A 20 V 400 kHz
Second, the overshoot requirement at load release is then
considered and supposes two 220 m F capacitors in parallel
are used as an initially guess, such that:
L v + 2.56 m H
2
Thus, inductors with standard inductance values of
1.5 m H, 1.8 m H and 2.2 m H can be used. As a trade ? off
between smaller overshoot and better efficiency, the
average value of 1.8 m H inductor is selected.
Then, the maximum rated DC current is calculated by:
(20 V ? 1.836 V) 1.836 V
2 1.8 m H 400 kHz 20
+ 13.39 A
(eq. 46)
Therefore, inductor with maximum rated DC current of
14 A or larger can be used.
Finally, the DCR of inductor is 2.0 m W per m H of
inductance as a rule of thumb, then:
DCR + 2 m W
maximum VTT output current with VTT within regulation
window will also be reduced if the external voltage is lower
1 m H
1.8 m H + 3.6 m W
(eq. 47)
than VDDQ. Besides, the VTTI pin input must be bypassed
http://onsemi.com
24
相关PDF资料 |
PDF描述 |
|---|---|
| NCP5220MNR2G | IC CTLR PWM DUAL BUCK PWR 20-DFN |
| NCP5222MNR2G | IC CTLR BUCK 2CH 2PH 28QFN |
| NCP5252MNTXG | IC REG BUCK SYNC ADJ 2A 16QFN |
| NCP5314FTR2G | IC CTLR CPU 2/3/4 PHASE 32-LQFP |
| NCP5318FTR2G | IC CTLR CPU 2/3/4 PHASE 32-LQFP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| NCP5220 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:3−in−1 PWM Dual Buck and Linear Power Controller |
| NCP5220AMNR2 | 功能描述:DC/DC 开关控制器 3-in-1 PWM Dual Buck 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 |
| NCP5220AMNR2G | 功能描述:DC/DC 开关控制器 ANA DDR PWER CNTRLR 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 |
| NCP5220MNR2 | 功能描述:DC/DC 开关控制器 3-in-1 PWM Dual Buck 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 |
| NCP5220MNR2G | 功能描述:DC/DC 开关控制器 3-in-1 PWM Dual Buck Linear DDR 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 |
发布紧急采购，3分钟左右您将得到回复。