参数资料
| 型号： | NCP3218GMNR2G |
| 厂商： | ON Semiconductor |
| 文件页数： | 24/35页 |
| 文件大小： | 0K |
| 描述： | IC CTLR CPU SYNC BUCK 7BIT 48QFN |
| 标准包装： | 2,500 |
| 应用： | 控制器，Intel IMVP-6.5? |
| 输入电压： | 3.3 V ~ 22 V |
| 输出数： | 1 |
| 输出电压： | 0.013 V ~ 1.5 V |
| 工作温度： | -40°C ~ 100°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 48-WFQFN 裸露焊盘 |
| 供应商设备封装： | 48-QFN（6x6） |
| 包装： | 带卷 (TR) |
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ADP3212, NCP3218, NCP3218G
R T +
V VID ) 1.0 V
* 16 k W
R R
C R
R RPM + * 0.5 k W
V VID ) 1.0 V f SW
I R +
V VID (1 * D MIN )
L
f SW
V VID R O 1 * (n D MIN )
V RIPPLE
f SW
R T +
* 16 k W
L w
+ 528 nH
Application Information
The design parameters for a typical IMVP ? 6.5 ? compliant
CPU core VR application are as follows:
? Maximum input voltage (V INMAX ) = 19 V
? Minimum input voltage (V INMIN ) = 8.0 V
? Output voltage by VID setting (V VID ) = 1.05 V
? Maximum output current (I O ) = 52 A
? Droop resistance (R O ) = 1.9 m W
? Nominal output voltage at 40 A load (V OFL ) = 0.9512 V
? Static output voltage drop from no load to full load
( D V) = V ONL ? V OFL = 1.05 V ? 0.9512 V = 98 mV
? Maximum output current step ( D I O ) = 52 A
? Number of phases (n) = 2
? Switching frequency per phase ( ? SW ) = 300 kHz
? Duty cycle at maximum input voltage (D MAX ) = 0.13 V
? Duty cycle at minimum input voltage (D MIN ) = 0.055 V
Setting the Clock Frequency for PWM
In PWM operation, the APD3212/NCP3218/NCP3218G
uses a fixed ? frequency control architecture. The frequency
is set by an external timing resistor (RT). The clock
frequency and the number of phases determine the switching
frequency per phase, which relates directly to the switching
losses and the sizes of the inductors and input and output
capacitors. For a dual ? phase design, a clock frequency of
600 kHz sets the switching frequency to 300 kHz per phase.
This selection represents the trade ? off between the
switching losses and the minimum sizes of the output filter
components. To achieve a 600 kHz oscillator frequency at a
VID voltage of 1.2 V, RT must be 181 k W . Alternatively, the
value for RT can be calculated by using the following
equation:
2 n f SW 9 pF (eq. 1)
where:
9 pF and 16 k W are internal IC component values.
V VID is the VID voltage in volts.
n is the number of phases.
? SW is the switching frequency in hertz for each phase.
For good initial accuracy and frequency stability, it is
recommended to use a 1% resistor.
When VARFREQ pin is connected to ground, the
switching frequency does not change with VID. The value
for RT can be calculated by using the following equation.
1.0 V
n 2 f SW 9 pF (eq. 2)
Setting the Switching Frequency for
RPM Operation of Phase 1
During the RPM operation of Phase 1, the APD3212/
NCP3218/NCP3218G runs in pseudoconstant frequency if
the load current is high enough for continuous current mode.
While in DCM, the switching frequency is reduced with the
load current in a linear manner.
To save power with light loads, lower switching frequency
is usually preferred during RPM operation. However, the
V CORE ripple specification of IMVP ? 6.5 sets a limitation
for the lowest switching frequency. Therefore, depending on
the inductor and output capacitors, the switching frequency
in RPM can be equal to, greater than, or less than its
counterpart in PWM.
A resistor from RPM to GND sets the pseudo constant
frequency as following:
2 R T A R (1 * D) V VID
(eq. 3)
where:
A R is the internal ramp amplifier gain.
C R is the internal ramp capacitor value.
R R is an external resistor on the RAMPADJ pin to set the
internal ramp magnitude.
Soft Start and Current Limit Latch ? Off Delay Times
Inductor Selection
The choice of inductance determines the ripple current of
the inductor. Less inductance results in more ripple current,
which increases the output ripple voltage and the conduction
losses in the MOSFETs. However, this allows the use of
smaller ? size inductors, and for a specified peak ? to ? peak
transient deviation, it allows less total output capacitance.
Conversely, a higher inductance results in lower ripple
current and reduced conduction losses, but it requires
larger ? size inductors and more output capacitance for the
same peak ? to ? peak transient deviation. For a multi ? phase
converter, the practical value for peak ? to ? peak inductor
ripple current is less than 50% of the maximum dc current
of that inductor. Equation 4 shows the relationship between
the inductance, oscillator frequency, and peak ? to ? peak
ripple current. Equation 5 can be used to determine the
minimum inductance based on a given output ripple voltage.
(eq. 4)
L w (eq. 5)
Solving Equation 5 for a 16 mV peak ? to ? peak output
ripple voltage yields:
1.05 V 1.9 m W (1 * 2 0.055)
300 kHz 16 mV
If the resultant ripple voltage is less than the initially
selected value, the inductor can be changed to a smaller
value until the ripple value is met. This iteration allows
optimal transient response and minimum output decoupling.
The smallest possible inductor should be used to minimize
the number of output capacitors. Choosing a 490 nH
inductor is a good choice for a starting point, and it provides
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| NCP3218MNR2G | 功能描述:DC/DC 开关控制器 IMVP6.5 BUCK CONTROLLER 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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