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参数资料
| 型号： | ISL8009EVAL1Z |
| 厂商： | Intersil |
| 文件页数： | 10/13页 |
| 文件大小： | 0K |
| 描述： | EVALUATION BOARD FOR ISL8009 |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 1，非隔离 |
| 输出电压： | 1.8V |
| 电流 - 输出： | 1.5A |
| 输入电压： | 2.7 ~ 5.5 V |
| 稳压器拓扑结构： | 降压 |
| 频率 - 开关： | 1.6MHz |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | ISL8009 |
ISL8009A
Cycle
Theory of Operation
The ISL8009A is a step-down switching regulator optimized for
battery-powered handheld applications. The regulator operates
at 1.6MHz fixed switching frequency under heavy load condition
to allow small external inductor and capacitors to be used for
minimal printed-circuit board (PCB) area. At light load, the
regulator reduces the switching frequency, unless forced to the
fixed frequency to minimize the switching loss and to maximize
the battery life. The quiescent current when the output is not
loaded is typically only 17μA. The supply current is typically only
0.1μA when the regulator is shutdown.
PWM Control Scheme
The ISL8009A employes the current-mode pulse-width
modulation (PWM) control scheme for fast transient response
and pulse-by-pulse current limiting. Figure 25 shows the block
diagram. The current loop consists of the oscillator, the PWM
comparator COMP, the current sensing circuit, and the slope
compensation for the current loop stability. The current sensing
circuit consists of the resistance of the P-Channel MOSFET when
it is turned on and the current sense amplifier CSA. The gain for
the current sensing circuit is typically 0.4V/A. The control
reference for the current loops comes from the error amplifier
EAMP of the voltage loop.
The PWM operation is initialized by the clock from the oscillator.
The P-Channel MOSFET is turned on at the beginning of a PWM
cycle and the current in the MOSFET starts to ramp up. When the
sum of the current amplifier CSA and the compensation slope
(0.675V/μs) reach the control reference of the current loop, the
PWM comparator COMP sends a signal to the PWM logic to turn
off the P-MOSFET and to turn on the N-Channel MOSFET. The
N-MOSFET stays on until the end of the PWM cycle. Figure 26
shows the typical operating waveforms during the PWM operation.
The dotted lines illustrate the sum of the compensation ramp and
the current-sense amplifier CSA output.
The output voltage is regulated by controlling the reference
voltage to the current loop. The bandgap circuit outputs a 0.8V
reference voltage to the voltage control loop. The feedback signal
comes from the VFB pin. The soft-start block only affects the
operation during the start-up and will be discussed separately.
The error amplifier is a transconductance amplifier that converts
the voltage error signal to a current output. The voltage loop is
internally compensated with the 30pF and 300k Ω RC network.
The maximum EAMP voltage output is precisely clamped to the
bandgap voltage (1.172V).
V EAMP
V CSA1
Duty
DUTY
CYCLE
I L
V OUT
FIGURE 26. PWM OPERATION WAVEFORMS
SKIP Mode
The ISL8009A enters a pulse-skipping mode at light load to
minimize the switching loss by reducing the switching frequency.
Figure 27 illustrates the skip-mode operation. A zero-cross
sensing circuit shown in Figure 25 monitors the N-MOSFET
current for zero crossing. When 8 consecutive cycles of the N-
MOSFET crossing zero are detected, the regulator enters the skip
mode. During the 8 detecting cycles, the current in the inductor is
allowed to become negative. The counter is reset to zero when
the current in any cycle does not cross zero.
Clock
CLOCK
Load Current
I L
Cycles
8 8 CYCLES
Current LIMIT
CURRENT Limit
LOAD CURRENT
Nominal
0
Nominal
NOMINAL + +1.5%
V OUT
NOMINAL
FIGURE 27. SKIP MODE OPERATION WAVEFORMS
10
FN6656.3
February 28, 2013
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相关代理商/技术参数 |
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|---|---|
| ISL8009IRZ-T | 制造商:Intersil Corporation 功能描述:CONV DC-DC SGL-OUT STEP DOWN 8DFN EP - Tape and Reel 制造商:Intersil Corporation 功能描述:Voltage Regulators - Switching Regulators W/ANNEAL LW IQ 1 5A BUCKG W/INTEGRTD FE |
| ISL8010 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Monolithic 600mA Step-Down Regulator with Low Quiescent Current |
| ISL8010_06 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Monolithic 600mA Step-Down Regulator with Low Quiescent Current |
| ISL80101 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:High Performance 1A LDO |
| ISL80101_11 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:High Performance 1A LDO |
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