参数资料
| 型号： | ISL6444CAZ-T |
| 厂商： | Intersil |
| 文件页数： | 8/19页 |
| 文件大小： | 0K |
| 描述： | IC CONTROLLER DDR 28-QSOP |
| 标准包装： | 2,500 |
| 应用： | 控制器，DDR |
| 输入电压： | 4.5 V ~ 24 V |
| 输出数： | 2 |
| 输出电压： | 0.9 V ~ 5.5 V |
| 工作温度： | -10°C ~ 85°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) |
ISL6444
Description
Operation
The ISL6444 is a dual channel PWM controller intended for
use in power supplies for graphic chipset, SDRAM, DDR
DRAM or other low voltage power applications in modern
notebook and sub-notebook PCs. The IC integrates two
1.5V, the power good (PGOOD), the mode control, and the
fault functions are enabled, as depicted in Figure 1.
EN
1
control circuits for two synchronous buck converters. The
output voltage of each controller can be set in the range of
2
0.9V
1.5V
SOFT
0.9V to 5.5V by an external resistive divider. Out-of-phase
operation with 180° phase shift reduces input current ripple.
The synchronous buck converters can operate from either
3
VOUT
an unregulated DC source such as a notebook battery with a
voltage ranging from 5.0V to 24V, or from a regulated system
4
PGOO D
rail of 3.3V or 5V. In either mode of operation, the controller
is biased from the +5V source.
Ch1 5.0V
Ch3 1.0V
Ch2 2.0V
Ch4 5.0V
M1.00ms
1.5V × Csoft
T SOFT = ----------------------------------
5 μ A
The controllers operate in the current mode with input
voltage feed-forward for simplified feedback loop
compensation and reduced effect of the input voltage
variation. An integrated feedback loop compensation
dramatically reduces the number of external components.
Depending on the load level, converters can operate either
in a fixed-frequency mode or in a hysteretic mode.
Switch-over to the hysteretic mode operation at light loads
improves the converters' efficiency and prolongs battery run
time. The hysteretic mode of operation can be inhibited
independently for each channel if a variable frequency
operation is not desired.
The ISL6444 has a special means to rearrange its internal
FIGURE 1. START-UP
This completes the soft start sequence. Further rise of pin
voltage does not affect the output voltage. During the
soft-start, the converter always operates in continuous
conduction mode independently of the load level or FCCM
pin potential.
The soft-start time (the time from the moment when EN
becomes high to the moment when PGOOD is reported) is
determined by Equation 1.
(EQ. 1)
The time it takes the output voltage to come into regulation
can be obtained from Equation 2.
architecture into a complete DDR solution. When DDR input
is set high, the second channel can provide the capability to
T RISE = 0.6 × T SOFT
(EQ. 2)
track the output voltage of the first channel. The buffered
reference voltage required by DDR memory chips is also
provided.
Initialization
The ISL6444 initializes if at least one of the enable pins is
set high. The Power-On Reset (POR) function continually
monitors the bias supply voltage on the VCC pin and initiates
soft-start operation after the input supply voltage exceeds
4.5V. Should this voltage drop lower than 4.0V, the POR
disables the chip.
Having such a spread between the time when the output
voltage reaches the regulation point and the moment when
PGOOD is reported allows for a fault-safe test mode by
means of an external circuit that clamps the SOFT pin
voltage on the level 0.9V < V SOFT < 1.5V.
Output Voltage Program
The output voltage of either channel is set by a resistive divider
from the output to ground. The center point of the divider is
connected to VSEN pin as shown in Figure 2. The output
voltage value is determined by Equation 3.
V O = ----------------------------------------------
Soft-Start
0.9V ? ( R1 + R2 )
R2
(EQ. 3)
When soft start is initiated, the voltage on the SOFT pin of
the enabled channel starts to ramp gradually due to the 5 μ A
current sourced into the external soft-start capacitor. The
output voltage starts to follow the soft-start voltage.
When the SOFT pin voltage reaches a level of 0.9V, the
output voltage comes into regulation while the soft-start pin
voltage continues to rise. When the SOFT voltage reaches
8
Where 0.9V is the value of the internal reference. The VSEN
pin voltage is also used by the controller for the power good
function and to detect undervoltage and overvoltage
conditions.
Automatic Operation Mode Control
In nominal currents the synchronous buck converter
operates in continuous-conduction constant-frequency
mode. This mode of operation achieves higher efficiency
due to the substantially lower voltage drop across the
FN9069.3
April 12, 2007
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL6445EVAL3Z | 功能描述:EVALUATION BOARD FOR ISL6445 RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| ISL6445IAZ | 功能描述:IC REG CTRLR BUCK PWM CM 24-QSOP 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) |
| ISL6445IAZS2695 | 制造商:Intersil Corporation 功能描述: |
| ISL6445IAZ-TK | 功能描述:IC REG CTRLR BUCK PWM CM 24-QSOP 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) |
| ISL6445IAZ-TKS2645 | 制造商:Intersil Corporation 功能描述:DC DC CNTRLR DUAL-OUT STEP DOWN 4.5V TO 24V 24QSOP W - Tape and Reel |
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