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参数资料
| 型号： | ISL8112EVAL1Z |
| 厂商： | Intersil |
| 文件页数： | 19/27页 |
| 文件大小： | 0K |
| 描述： | EVALUATION BOARD FOR ISL8112 |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 2，非隔离 |
| 输出电压： | 0.7 ~ 5.5 V |
| 电流 - 输出： | 200mA |
| 输入电压： | 5.5 ~ 25 V |
| 稳压器拓扑结构： | 降压 |
| 频率 - 开关： | 可调式 |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | ISL8112 |
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ISL8112
current-limit threshold by an amount equal to the inductor
ripple current. Therefore, the exact current-limit
characteristic and maximum load capability are a function of
the current-limit threshold, inductor value and input and
output voltage.
I PEAK
A negative current limit prevents excessive reverse inductor
currents when VOUT sinks current. The negative
current-limit threshold is set to approximately 120% of the
positive current limit and therefore tracks the positive current
limit when ILIM_ is adjusted. The current-limit threshold is
adjusted with an external resistor for ISL8112 at ILIM_. The
current-limit threshold adjustment range is from 20mV to
200mV. In the adjustable mode, the current-limit threshold
voltage is 1/10th the voltage at ILIM_. The voltage at ILIM
I LOAD
Δ I
pin is the product of 5μA * R ILIM . The threshold defaults to
100mV when ILIM_ is connected to VCC. The logic
threshold for switch-over to the 100mV default value is
I LIMIT
I LOAD(MAX)
I LIM ( VAL ) = I LOAD - Δ I
2
TIME
FIGURE 24. “VALLEY” CURRENT LIMIT THRESHOLD POINT
For lower power dissipation, the ISL8112 uses the
on-resistance of the synchronous rectifier as the
current-sense element. Use the worst-case maximum value
for r DS(ON) from the MOSFET data sheet. Add some margin
for the rise in r DS(ON) with temperature. A good general rule
is to allow 0.5% additional resistance for each °C of
temperature rise. The ISL8112 controller has a built-in 5μA
current source as shown in Figure 25. Place the hottest
power MOSEFTs as close to the IC as possible for best
thermal coupling. The current limit varies with the on-
resistance of the synchronous rectifier. When combined with
the undervoltage-protection circuit, this current-limit method
is effective in almost every circumstance.
ILIM_
approximately VCC - 1V.
The PC board layout guidelines should be carefully
observed to ensure that noise and DC errors do not corrupt
the current-sense signals at PH_.
MOSFET Gate Drivers (UG_, LG_)
The UG_ and LG_ gate drivers sink 2.0A and 3.3A
respectively of gate drive, ensuring robust gate drive for
high-current applications. The UG_ floating high-side
MOSFET drivers are powered by diode-capacitor charge
pumps at BOOT_. The LG_ synchronous-rectifier drivers are
powered by PVCC.
The internal pull-down transistors that drive LG_ low have a
0.6 Ω typical on-resistance. These low on-resistance
pull-down transistors prevent LG_ from being pulled up
during the fast rise time of the inductor nodes due to
capacitive coupling from the drain to the gate of the low-side
synchronous-rectifier MOSFETs. However, for high-current
applications, some combinations of high- and low-side
MOSFETs may cause excessive gate-drain coupling, which
leads to poor efficiency and EMI-producing shoot-through
currents. Adding a 4.7 Ω resistor in series with BOOT_
increases the turn-on time of the high-side MOSFETs at the
expense of efficiency, without degrading the turn-off time
(Figure 26).
5V
R ILIM
VILIM
VCC
5μA
9R
R
TO CURRENT
LIMIT LOGIC
PVCC
BOOT_
UG_
4.7 Ω
VIN
Q1
C BOOT
PH_
OUT_
FIGURE 25. CURRENT LIMIT BLOCK DIAGRAM
19
ISL8112
FIGURE 26. REDUCING THE SWITCHING-NODE RISE TIME
FN6396.1
August 10, 2010
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| ISL8112IRZ | 功能描述:IC REG DL BCK/LINEAR SYNC 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式 系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（3），线性（LDO）（2） 功能:任何功能 输出数:5 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器 电压/电流 - 输出 2:控制器 电压/电流 - 输出 3:控制器 带 LED 驱动器:无 带监控器:无 带序列发生器:是 电源电压:5.6 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* |
| ISL8112IRZ-T | 功能描述:IC REG DL BCK/LINEAR SYNC 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式 系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（3），线性（LDO）（2） 功能:任何功能 输出数:5 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器 电压/电流 - 输出 2:控制器 电压/电流 - 输出 3:控制器 带 LED 驱动器:无 带监控器:无 带序列发生器:是 电源电压:5.6 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* |
| ISL8115 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:High Voltage Synchronous Buck PWM Controller with Integrated Gate Driver and Current Sharing Capability |
| ISL8115EVAL1Z | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:High Voltage Synchronous Buck PWM Controller with Integrated Gate Driver and Current Sharing Capability |
| ISL8115EVAL2Z | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:High Voltage Synchronous Buck PWM Controller with Integrated Gate Driver and Current Sharing Capability |
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