参数资料
型号: NCP5222MNR2G
厂商: ON Semiconductor
文件页数: 14/28页
文件大小: 0K
描述: IC CTLR BUCK 2CH 2PH 28QFN
标准包装: 4,000
应用: 多相控制器
电流 - 电源: 2.5mA
电源电压: 4.5 V ~ 27 V
工作温度: -40°C ~ 85°C
安装类型: 表面贴装
封装/外壳: 28-VFQFN 裸露焊盘
供应商设备封装: 28-QFN(4x4)
包装: 带卷 (TR)
NCP5222
Where I O1 is the loading current in the power rail V O1 , and
I O2 is the loading current in the power rail V O2 . Using of
Equations 5, 6, 7, 8, 15, and 16 gives:
I FB2 + k IL2_IFB2 @ I O2 * k IL1_IFB2 @ I O1 ) k IL1_IFB2 ) k IL2_IFB2
11
@ V ref2 * 1 ) R @ V ref1 ) R 21 @ k IL1_IFB2 @ I O1 * k IL2_IFB2 @ I O2
@
R
1 ) R
21
24
R
14
R ON_S ) R 21 @ k IL1_IFB2 ) k IL2_IFB2
(eq. 17)
where
continuous ? conduction mode (CCM). To reduce the
R CS12
R CS22
k IL1_IFB2 + G IFB2 @ G ICS1 @ R ICS1 @ k CS1 @ DCR 1
+ 1x10 ? 3 @ @ DCR 1
R CS11 ) R CS12
k IL2_IFB2 + G IFB2 @ G ICS2 @ R ICS2 @ k CS2 @ DCR 2
+ 1x10 ? 3 @ @ DCR 2
R CS21 ) R CS22
(eq. 18)
(eq. 19)
common input ripple and capacitors, the two channels /
phases operate 180 ° interleaved in CCM. To speed up
transient response and increase system sampling rate, an
internal 1.2 MHz high ? frequency oscillator is employed. A
digital circuitry divides down the high ? frequency clock
CLK_H and generates two interleaved 300 kHz clocks
(CLK1 and CLK2), which are delivered to the two PWM
control blocks as normal operation clocks.
@ 0.8 * 8 @ 10 ? 6 @ R 21 v V O2
R 24
R 21
To maintain the output voltage V O2 of the phase 2 in
certain regulation window in case of any fault or non ? ideal
conditions, such as the sharing switch is broken or has too
high on resistance, the injection current I FB2 has magnitude
limits as $ 9 m A. As a result, V O2 has a limited adjustable
range as
R 21
1 )
(eq. 20)
v 1 ) @ 0.8 ) 9 @ 10 ? 6 @ R 21
R 24
In an Ideal case that the sharing switch has very small on
resistance and the two phases matches perfectly, the
current ? sense input voltages in the two phases are equal, that
is
I L1 @ DCR 1 @ k CS1 + I L2 @ DCR 2 @ k CS2 (eq. 21)
Forced ? PWM Operation (FPWM Mode)
If the voltage level at the EN pin is a medium level around
1.95 V, the corresponding channel of the NCP5222 works
under forced ? PWM mode with fixed 300 kHz switching
frequency. In this mode, the low ? side gate ? drive signal is
forced to be the complement of the high ? side gate ? drive
signal and thus the converter always operates in CCM. This
mode allows reverse inductor current, in such a way that it
provides more accurate voltage regulation and fast transient
response. During soft ? start operation, the NCP5222
automatically runs in FPWM mode regardless of the EN
pin’s setting to guarantee smooth powering up.
Pulse ? Skipping Operation (Skip Mode)
Skip mode is enabled by pulling EN pin higher than
2.65 V, and then the corresponding channel works in
pulse ? skipping enabled operation. In medium and high load
DCR 1 @ k CS1 ) DCR 2 @ k CS2
DCR 1 @ k CS1 ) DCR 2 @ k CS2
DCR 1 @ k CS1 ) DCR 2 @ k CS2
Using of Equations 15, 16, and 21 gives
DCR 2 @ k CS2 @ I O1 ) I O2
I L1 +
DCR 1 @ k CS1 @ I O1 ) I O2
I L2 +
DCR 1 @ k CS1 @ I O1 * DCR 2 @ k CS2 @ I O2
I Share +
PWM Operation
(eq. 22)
(eq. 23)
(eq. 24)
range, the converter still runs in CCM, and the switching
frequency is fixed to 300 kHz. If the both channels run in
CCM, they operate interleaved. In light load range, the
converter automatically enters diode emulation and skip
mode to maintain high efficiency. The PWM on ? time in
discontinuous ? conduction mode (DCM) is adaptively
controlled to be similar to the PWM on ? time in CCM.
Transient Response Enhancement (TRE)
For a conventional trailing ? edge PWM controller in
CCM, the minimum response delay time is one switching
period in the worst case. To further improve transient
response, a transient response enhancement circuitry is
There are two available operation modes, which are
forced PWM mode and power ? saving skip mode, selected
by two different voltage levels at EN pin for each channel,
respectively. The operation modes can be external preset or
on ? line programmed.
The two channels / phases controlled by the NCP5222
share one input power rail. The both channels / phases
operate at a fixed 300 kHz normal switching frequency in
introduced to the NCP5222. The controller continuously
monitors the COMP signal, which is the output voltage of
the error amplifier, to detect load transient events. A desired
stable close ? loop system with the NCP5222 has a ripple
voltage in the COMP signal, which peak ? to ? peak value is
normally in a range from 200 mV to 500 mV. There is a
threshold voltage in each channel made in a way that a
filtered COMP signal pluses an offset voltage. Once a large
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