参数资料
| 型号： | ISL6556BCRZ-T |
| 厂商： | Intersil |
| 文件页数： | 15/24页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR MULTIPHASE VRM10 32-QFN |
| 标准包装： | 6,000 |
| 应用： | 控制器，Intel VR10X |
| 输入电压： | 3 V ~ 12 V |
| 输出数： | 4 |
| 输出电压： | 0.84 V ~ 1.6 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-VFQFN 裸露焊盘 |
| 供应商设备封装： | 32-QFN 裸露焊盘（5x5） |
| 包装： | 带卷 (TR) |
ISL6556B
on-the-fly VID changes in a controlled manner. Supervising
the safe output voltage transition within the DAC range of the
processor without discontinuity or disruption is a necessary
function of the core-voltage regulator.
The ISL6556B checks the VID inputs six times every
switching cycle. If the VID code is found to have changed,
the controller waits half of a complete cycle before executing
a 12.5mV change. If during the half-cycle wait period, the
difference between DAC level and the new VID code
changes sign, no change is made. If the VID code is more
than 1 bit higher or lower than the DAC (not recommended),
the controller will execute 12.5mV changes six times per
cycle until VID and DAC are equal. It is for this reason that it
is important to carefully control the rate of VID stepping in 1-
bit increments.
In order to ensure the smooth transition of output voltage
during VID change, a VID step change smoothing network is
required for an ISL6556B based voltage regulator. This
network is composed by a 1k ? internal resistor between the
output of DAC and the C REF between REF pin to ground.
The selection of C REF is based on the time duration for 1 bit
VID change and the allowable delay time.
Assuming the microprocessor controls the VID change at 1
bit every T VID , the relationship between C REF and T VID is
given by Equation 9.
is designed as 1 μ A/V/°C. The temperature coefficient of
MOSFET r DS(ON) is given by α . This is the ratio of the
change in resistance and the change in temperature.
Resistance is normalized to the value at 25°C and the value
of α is typically between 0.35%/°C and 0.50%/°C.
According to Equation 10, a voltage regulator with 80%
thermal coupling coefficient between the controller and lower
MOSFET and 0.4% /°C temperature coefficient of MOSFET
r DS(ON) requires a 5k ? TCOMP resistor.
Initialization
Prior to initialization, proper conditions must exist on the
enable inputs and VCC. When the conditions are met, the
controller begins soft-start. Once the output voltage is within
the proper window of operation, PGOOD asserts logic.
Enable and Disable
While in shutdown mode, the PWM outputs are held in a
high-impedance state to assure the drivers remain off. The
following input conditions must be met before the ISL6556B
is released from shutdown mode.
1. The bias voltage applied at VCC must reach the internal
power-on reset (POR) rising threshold. Once this
threshold is reached, proper operation of all aspects of
the ISL6556B is guaranteed. Hysteresis between the
rising and falling thresholds assure that once enabled,
C REF = 0.004X T VID
(EQ. 9)
the ISL6556B will not inadvertently turn off unless the
bias voltage drops substantially (see Electrical
Specifications ).
As an example, for a VID step change rate of 5 μ s per bit, the
value of C REF is 22nF based on Equation 9.
ISL6556B INTERNAL CIRCUIT
EXTERNAL CIRCUIT
Temperature Compensation
The MOSFET r DS(ON) varies in proportion to varying
VCC
+ 12 V
temperature. This means that a circuit using r DS(ON) to
sense channel current is subject to a corresponding error in
current measurement. In order to compensate for this
POR
CIRCUIT
ENABLE
COMPARATOR
EN
10.7k ?
temperature-related error, a temperature compensation
+
circuit is provided within ISL6561. This circuit senses the
internal IC temperature and, based on a resistor-selectable
scaling factor, adjust the droop current flow to the FB pin.
When the TCOMP resistor is properly selected, the droop
current can accurately represent the load current to achieve
a linear, temperature-independant load line.
The value of the Tcomp resistor can be determined using
Equation 10.
SOFT-START
AND
FAULT LOGIC
-
1.24V
1.40k ?
ENLL
(ISL6556BCR ONLY)
α
R TCOMP = ----------------------
K T K TC
(EQ. 10)
FIGURE 8. POWER SEQUENCING USING THRESHOLD-
SENSITIVE ENABLE (EN) FUNCTION
In Equation 10, K T is the temperature coupling coefficient
between the ISL6561 and the lower MOSFET. It represents
how closely the controller temperature tracks the lower
MOSFET temperature. The value of K T is typically between
75% and 100%. K TC is the temperature dependant
transconductance of internal compensation circuit. Its value
15
2. The ISL6556B features an enable input (EN) for power
sequencing between the controller bias voltage and
another voltage rail. The enable comparator holds the
ISL6556B in shutdown until the voltage at EN rises above
1.24V. The enable comparator has about 100mV of
hysteresis to prevent bounce. It is important that the
FN9097.4
December 28, 2004
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL6557 WAF | 制造商:Intersil Corporation 功能描述: |
| ISL6557ACB | 功能描述:IC REG CTRLR BUCK PWM VM 24-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| ISL6557ACB-T | 功能描述:IC REG CTRLR BUCK PWM VM 24-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| ISL6557ACBZ | 功能描述:IC REG CTRLR BUCK PWM VM 24-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
| ISL6557ACBZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 24-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
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