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| 型号： | ISL8012IRZ-T |
| 厂商： | Intersil |
| 文件页数： | 12/17页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 2A 10DFN |
| 产品培训模块： | Solutions for Test and Measurement Equipment Solutions for Industrial Control Applications |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.8 V ~ 5.5 V |
| 输入电压： | 2.7 V ~ 5.5 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 1MHz |
| 电流 - 输出： | 2A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-VFDFN 裸露焊盘 |
| 包装： | 标准包装 |
| 供应商设备封装： | 10-DFN（3x3） |
| 产品目录页面： | 1248 (CN2011-ZH PDF) |
| 其它名称： | ISL8012IRZ-TDKR |
ISL8012
Theory of Operation
The ISL8012 is a step-down switching regulator optimized for
battery-powered handheld applications. The regulator operates at
1MHz fixed switching frequency under heavy load conditions to
allow smaller external inductors 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 40μA. The supply current is typically only 0.1μA when
the regulator is shut down.
PWM Control Scheme
Pulling the MODE pin LOW (<0.4V) forces the converter into PWM
mode, regardless of output current. The ISL8012 employs the
current-mode pulse-width modulation (PWM) control scheme for
fast transient response and pulse-by-pulse current limiting. Figure 2
shows the block diagram. The current loop consists of the oscillator,
the PWM comparator, current sensing circuit and the slope
compensation for the current loop stability. The gain for the current
sensing circuit is typically 285mV/A. The control reference for the
current loops comes from the error amplifier's (EAMP) output.
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 slope compensation (675mV/μs)
reaches 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 turn on the N-Channel MOSFET. The N-MOSFET stays
on until the end of the PWM cycle. Figure 32 shows the typical
operating waveforms during the PWM operation. The dotted lines
illustrate the sum of the slope compensation ramp and the
current-sense amplifier’s CSA output.
The output voltage is regulated by controlling the V EAMP voltage
to the current loop. The bandgap circuit outputs a 0.8V reference
voltage to the voltage 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 27pF and 390k ? RC network. The maximum EAMP
voltage output is precisely clamped to 1.47V.
CLOCK
8 CYCLES
I L
V EAMP
V CSA
DUTY
CYCLE
I L
V OUT
FIGURE 32. PWM OPERATION WAVEFORMS
SKIP Mode
Pulling the MODE pin HIGH (>1.4V) forces the converter into PFM
mode. The ISL8012 enters a pulse-skipping mode at light load to
minimize the switching loss by reducing the switching frequency.
Figure 33 illustrates the skip-mode operation. A zero-cross
sensing circuit shown in Figure 2 monitors the N-MOSFET current
for zero crossing. When 8 consecutive cycles of the inductor
current 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.
Once the skip mode is entered, the pulse modulation starts being
controlled by the SKIP comparator shown in Figure 2. Each pulse
cycle is still synchronized by the PWM clock. The P-MOSFET is turned
on at the clock's rising edge and turned off when the output is
higher than 1.5% of the nominal regulation or when its current
reaches the peak Skip current limit value. Then the inductor current
is discharging to zero Ampere and stays at zero. The internal clock is
disabled. The output voltage reduces gradually due to the load
current discharging the output capacitor. When the output voltage
drops to the nominal voltage, the P-MOSFET will be turned on again
at the rising edge of the internal clock as it repeats the previous
operations.
The regulator resumes normal PWM mode operation when the
output voltage drops 1.5% below the nominal voltage.
SKIP CURRENT LIMIT
LOAD CURRENT
0
NOMINAL +1.5%
V OUT
NOMINAL
FIGURE 33. SKIP MODE OPERATION WAVEFORMS
12
December 1, 2011
FN6616.2
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL8012IRZ-T7A | 功能描述:IC REG BUCK SYNC ADJ 2A 10DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:两者兼有 输出数:1 输出电压:5V，1 V ~ 10 V 输入电压:3.5 V ~ 28 V PWM 型:电流模式 频率 - 开关:220kHz ~ 1MHz 电流 - 输出:600mA 同步整流器:无 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:16-SSOP（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:16-QSOP |
| ISL8013 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:3A Low Quiescent Current 1MHz High Efficiency Synchronous Buck Regulator |
| ISL80136 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:40V, Low Quiescent Current, 50mA Linear Regulator |
| ISL80136IBEAJZ | 功能描述:低压差稳压器 - LDO 40V LW QUIESCENT CUR 50MALDO EP 8L (0.15) RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| ISL80136IBEAJZ-T | 制造商:Intersil Corporation 功能描述:40V, LOW QUIESCENT CURRENT, 50MA LDO, EP 8L SOIC (0.15) - Tape and Reel 制造商:Intersil Corporation 功能描述:IC REG LDO ADJ 0.05A 8SOIC 制造商:Intersil 功能描述:40V LW QUIESCENT CUR 50MALDO EP 8L0 15 |
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