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| 型号： | ISL8112EVAL1Z |
| 厂商： | Intersil |
| 文件页数： | 12/27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
provide the PWM ramp signal; thus the output filter
capacitor's ESR acts as a current-feedback resistor. The
high-side switch on-time is determined by a one-shot whose
period is inversely proportional to input voltage and directly
proportional to output voltage. Another one-shot sets a
minimum off-time (300ns typ). The on-time one-shot triggers
when the following conditions are met: the error
comparator's output is high, the synchronous rectifier current
is below the current-limit threshold, and the minimum off time
one-shot has timed out.
where:
? V DROP1 is the sum of the parasitic voltage drops in the
inductor discharge path, including synchronous rectifier,
inductor, and PC board resistances
? V DROP2 is the sum of the parasitic voltage drops in the
charging path, including high-side switch, inductor, and PC
board resistances
? t ON is the on-time calculated by the ISL8112.
TABLE 2. APPROXIMATE K-FACTOR ERRORS
ON-TIME ONE-SHOT (FS)
SWITCHING
APPROXIMATE
Each PWM core includes a one-shot that sets the high-side
switch on-time for each controller. Each fast, low-jitter,
SMPS
FREQUENCY K-FACTOR
(kHz) (μs)
K-FACTOR
ERROR (%)
adjustable one-shot includes circuitry that varies the on-time
(FS = GND,
400
2.5
±10
in response to battery and output voltage. The high-side
switch on-time is inversely proportional to the battery voltage
VREF1, or OPEN),
VSEN1
V IN
as measured by the V IN input and proportional to the output
voltage. This algorithm results in a nearly constant switching
frequency despite the lack of a fixed-frequency clock
generator. The benefit of a constant switching frequency is
that the frequency can be selected to avoid noise-sensitive
frequency regions:
K ( V OUT + I LOAD ? r DSON ( LOWERQ ) )
(EQ. 1)
t ON = ------------------------------------------------------------------------------------------------------
(FS = GND),
VSEN2
(FS = VCC),
VSEN1
(FS = VCC,
VREF1, or OPEN),
VSEN2
500
200
300
2.0
5.0
3.3
±10
±10
±10
See Table 2 for approximate K- factors. Switching frequency
increases as a function of load current due to the increasing
drop across the synchronous rectifier, which causes a faster
inductor-current discharge ramp. On-times translate only
roughly to switching frequencies. The on-times guaranteed
in the Electrical Characteristics are influenced by switching
delays in the external high-side power MOSFET. Also, the
dead-time effect increases the effective on-time, reducing
the switching frequency. It occurs only in PWM mode
(MODE = VCC) and during dynamic output voltage
transitions when the inductor current reverses at light or
negative load currents. With reversed inductor current, the
inductor's EMF causes PH_ to go high earlier than normal,
extending the on-time by a period equal to the UG-rising
dead time.
For loads above the critical conduction point, the actual
switching frequency is:
V OUT + V DROP1
t ON ( V IN + V DROP2 )
f = -------------------------------------------------------
12
(EQ. 2)
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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