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参数资料
| 型号： | ISL6227CA |
| 厂商： | INTERSIL CORP |
| 元件分类： | 稳压器 |
| 英文描述： | Dual Mobile-Friendly PWM Controller with DDR Option |
| 中文描述： | DUAL SWITCHING CONTROLLER, 345 kHz SWITCHING FREQ-MAX, PDSO28 |
| 封装： | 0.150 INCH, PLASTIC, SSOP-28 |
| 文件页数： | 9/27页 |
| 文件大小： | 834K |
| 代理商： | ISL6227CA |
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17
FN9094.7
May 4, 2009
output signal before the PWM comparator input. This
effectively creates an internal current control loop.
The resistor connected to the ISEN pin sets the gain in the
current sensing. The following expression estimates the
required value of the current sense resistor, depending on
the maximum continuous load current, and the value of the
MOSFETs rDS(ON), assuming the ISEN pin sources 75A
current.
Because the current sensing circuit is a sample-and-hold
type, the information obtained at the last moment of the
sampling is used. This current sensing circuit samples the
inductor current very close to its peak value. The current
feedback essentially injects a resistor Ri in series with the
original LC filter as shown in Figure 37, where the
sample-and-hold effect of the current loop has been ignored.
Vc and Vo are small signal components extracted from its
DC operation points.
The value of the injected resistor can be estimated by
Equation 7:
Ri is in kΩ, and rDS and RCS are in Ω . VIN divided by Vramp,
is defined as Gm, which is a constant 8dB or 18dB for both
channels in dual switcher applications, when VIN is above
3V. Refer to Table 1 for the ramp amplitude in different VIN
pin connections. The feed-forward effect of the VIN is
reflected in Gm. VC is defined as the error amplifier output
voltage.
The small signal transfer function from the error amplifier
output voltage Vc to the output voltage Vo can be written in
Equation 8:
The DC gain is derived by shorting the inductor and opening
the capacitor. There is one zero and two poles in this transfer
function. The zero is related to ESR and the output
capacitor.
The first pole is a low frequency pole associated with the
output capacitor and its charging resistors. The inductor can
be regarded as short. The second pole is the high frequency
pole related to the inductor. At high frequency the output
capacitor can be regarded as a short circuit. By
approximation, the poles and zero are inversely proportional
to the time constants, associated with inductor and capacitor,
Since the current loop separates the LC resonant poles into
two distant poles, and ESR zero tends to cancel the high
frequency pole, the second order system behaves like a first
order system. This control method simplifies the design of
the internal compensator and makes it possible to
accommodate many applications having a wide range of
parameters.
The schematics for the internal compensator is shown in
Figure 38.
TABLE 1. PWM COMPARATOR RAMP AMPLITUDE FOR
DUAL SWITCHER APPLICATION
VIN PIN CONNECTIONS
VRAMP
AMPLITUDE
Ch1 and Ch2 Input Voltage
Input voltage >4.2V
VIN/8
Input voltage <4.2V
1.25V
GND
1.25V
R
CS
I
MAX
r
DS ON
()
75
μA
------------------------------------------
=
140
Ω
–
(EQ. 6)
FIGURE 37. THE EQUIVALENT CIRCUIT OF THE POWER
STAGE WITH CURRENT LOOP INCLUDED
+
-
Gm*Vc
Ri
Lo
DCR
Co
Ro
Vo
ESR
+
-
R
i
V
IN
V
ramp
-----------------
r
DS ON
()
R
CS
140
+
----------------------------
4.4k
Ω
=
(EQ. 7)
TABLE 2. PWM COMPARATOR RAMP VOLTAGE AMPLITUDE
FOR DDR APPLICATION
VIN PIN CONNECTION
VRAMP
AMPLITUDE
Ch1
Input Voltage
Input voltage >4.2V
Vin/8
Input voltage <4.2V
1.25V
GND
1.25V
Ch2
Input voltage >4.2V
0.625V
GND
1.25V
Gs
()
G
m
R
o
R
i
DCR
R
o
++
---------------------------------------
s
Wz
---------
1
+
s
Wp1
-------------
1
+
s
Wp2
-------------
1
+
---------------------------------------------------------
=
(EQ. 8)
Wz
1
ESR*C
o
------------------------
=
(EQ. 9)
Wp1
1
ESR
R
i
DCR
+
() R
o
||
+
()*C
o
-------------------------------------------------------------------------------
=
(EQ.10)
Wp2
R
i
DCR
ESR
++
R
o
||
L
o
----------------------------------------------------------
=
(EQ.11)
ISL6227
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| ISL6227CA-T | 功能描述:IC CONTROLLER DDR, DDR2 28QSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,000 系列:- 应用:电源，ICERA E400，E450 输入电压:4.1 V ~ 5.5 V 输出数:10 输出电压:可编程 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:42-WFBGA，WLCSP 供应商设备封装:42-WLP 包装:带卷 (TR) |
| ISL6227CAZ | 功能描述:电流型 PWM 控制器 VER OF ISL6227CA RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| ISL6227CAZS2698 | 功能描述:IC CONTROLLER DDR, DDR2 28QSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| ISL6227CAZ-T | 功能描述:电流型 PWM 控制器 VER OF ISL6227CA-T RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| ISL6227CAZ-TS2698 | 功能描述:IC CONTROLLER DDR, DDR2 28QSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
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