参数资料
| 型号： | ISL6227CA-T |
| 厂商： | Intersil |
| 文件页数： | 17/27页 |
| 文件大小： | 0K |
| 描述： | IC CONTROLLER DDR, DDR2 28QSOP |
| 标准包装： | 2,500 |
| 应用： | 控制器，DDR，DDR2 |
| 输入电压： | 5 V ~ 28 V |
| 输出数： | 2 |
| 输出电压： | 0.9 V ~ 5.5 V |
| 工作温度： | -10°C ~ 100°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 28-SSOP/QSOP |
| 包装： | 带卷 (TR) |
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ISL6227
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
TABLE 2. PWM COMPARATOR RAMP VOLTAGE AMPLITUDE
FOR DDR APPLICATION
VRAMP
current sensing. The following expression estimates the
VIN PIN CONNECTION
AMPLITUDE
required value of the current sense resistor, depending on
Ch1
Input Voltage
Input voltage >4.2V
Vin/8
the maximum continuous load current, and the value of the
MOSFETs r DS(ON) , assuming the ISEN pin sources 75μA
current.
GND
Input voltage <4.2V
1.25V
1.25V
I MAX ? r DS ( ON )
75 μ A
R CS = ------------------------------------------ – 140 Ω
(EQ. 6)
Ch2
Input voltage >4.2V
GND
0.625V
1.25V
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
The small signal transfer function from the error amplifier
output voltage V c to the output voltage V o can be written in
Equation 8:
? --------- + 1 ?
G ( s ) = G m --------------------------------------- ---------------------------------------------------------
? ? ------------- + 1 ?
R i + DCR + R o ? s s
? Wp1
? ? Wp2
?
feedback essentially injects a resistor R i 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
s
R o ? Wz ?
------------- + 1
(EQ. 8)
DC operation points.
The DC gain is derived by shorting the inductor and opening
Ri
Lo
DCR
the capacitor. There is one zero and two poles in this transfer
Gm*Vc
+
-
Co
ESR
Ro
+
Vo
function. The zero is related to ESR and the output
capacitor.
The first pole is a low frequency pole associated with the
-
FIGURE 37. THE EQUIVALENT CIRCUIT OF THE POWER
STAGE WITH CURRENT LOOP INCLUDED
The value of the injected resistor can be estimated by
Equation 7:
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,
by Equations 9, 10 and 11:
R i = ----------------- ---------------------------- ? 4.4k Ω
Wz = ------------------------
V IN r DS ( ON )
V ramp R CS + 140
(EQ. 7)
1
ESR*C o
(EQ. 9)
Wp1 = -------------------------------------------------------------------------------
R i + DCR + ESR || R o
R i is in k Ω, and r DS and R CS are in Ω . V IN divided by V ramp ,
is defined as Gm, which is a constant 8dB or 18dB for both
channels in dual switcher applications, when V IN is above
3V. Refer to Table 1 for the ramp amplitude in different V IN
pin connections. The feed-forward effect of the V IN is
reflected in Gm. V C is defined as the error amplifier output
1
( ESR + ( R i + DCR ) || R o ) *C o
Wp2 = ----------------------------------------------------------
L o
(EQ.10)
(EQ.11)
voltage.
TABLE 1. PWM COMPARATOR RAMP AMPLITUDE FOR
DUAL SWITCHER APPLICATION
VRAMP
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
VIN PIN CONNECTIONS
AMPLITUDE
accommodate many applications having a wide range of
Ch1 and Ch2 Input Voltage
Input voltage >4.2V
Input voltage <4.2V
VIN/8
1.25V
parameters.
The schematics for the internal compensator is shown in
Figure 38.
GND
17
1.25V
FN9094.7
May 4, 2009
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
| ISL6227EVAL1 | 功能描述:EVALUATION BOARD 1 ISL6227 RoHS:否 类别:编程器，开发系统 >> 过时/停产零件编号 系列:- 标准包装:1 系列:- 传感器类型:CMOS 成像，彩色（RGB） 传感范围:WVGA 接口:I²C 灵敏度:60 fps 电源电压:5.7 V ~ 6.3 V 嵌入式:否 已供物品:成像器板 已用 IC / 零件:KAC-00401 相关产品:4H2099-ND - SENSOR IMAGE WVGA COLOR 48-PQFP4H2094-ND - SENSOR IMAGE WVGA MONO 48-PQFP |
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