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| 型号： | ISL6273IRZ |
| 厂商： | Intersil |
| 文件页数： | 9/12页 |
| 文件大小： | 0K |
| 描述： | IC BUCK SYNC ADJ 1.2A 10DFN |
| 产品培训模块： | Solutions for Industrial Control Applications |
| 标准包装： | 100 |
| 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： | 1.5MHz |
| 电流 - 输出： | 1.2A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | * |
| 封装/外壳： | * |
| 包装： | * |
| 供应商设备封装： | * |
ISL6273
Theory of Operation
The ISL6273 is a step-down switching regulator optimized
for battery-powered handheld applications. The regulator
operates at 1.5MHz 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 25 μ A. The supply current is typically only 0.1 μ A when
the regulator is shut down. The ISL6273 has four fixed
output voltage versions and one adjustable version.
PWM Control Scheme
The ISL6273 employs the current-mode pulse-width
modulation (PWM) control scheme for fast transient
response and pulse-by-pulse current limiting. Figure 17
shows the block diagram. The current loop consists of the
oscillator, the PWM comparator COMP, 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/ μ s) 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 to turn on the N-channel MOSFET. The
N-MOSFET stays on until the end of the PWM cycle.
Figure 18 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.
V EAMP
V CSA1
Duty
Cycle
I L
V OUT
FIGURE 18. PWM OPERATION WAVEFORMS
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 FB pin. The soft-start block
only affects the operation during the start-up and will be
discussed separately shortly. 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).
SKIP Mode
The ISL6273 enters a pulse-skipping mode at light load to
minimize the switching loss by reducing the effective
switching frequency. Figure 19 illustrates the skip-mode
operation. A zero-cross sensing circuit shown in Figure 17
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
I L
8 Cycles
Current Limit
Load Current
0
Nominal + 1.5%
V OUT
Nominal
FIGURE 19. SKIP MODE OPERATION WAVEFORMS
9
FN9256.0
March 7, 2006
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL6273IRZ-T | 功能描述:IC BUCK SYNC ADJ 1.2A 10DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:4.5V 输入电压:2.65 V ~ 4.35 V PWM 型:电流模式 频率 - 开关:3.5MHz 电流 - 输出:800mA 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:9-UFBGA，DSBGA 包装:Digi-Reel® 供应商设备封装:9-DSBGA（1.2x1.3） 其它名称:296-29764-6 |
| ISL6274AIRZ-TR5256 | 制造商:Intersil Corporation 功能描述: |
| ISL62771HRTZ | 功能描述:IC PWM CTRLR MULTIPHASE 40TQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:Robust Ripple Regulator™ (R³) 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,000 系列:- 应用:电源，ICERA E400，E450 输入电压:4.1 V ~ 5.5 V 输出数:10 输出电压:可编程 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:42-WFBGA，WLCSP 供应商设备封装:42-WLP 包装:带卷 (TR) |
| ISL62771HRTZ-T | 功能描述:IC PWM CTRLR MULTIPHASE 40TQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:Robust Ripple Regulator™ (R³) 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| ISL62771IRTZ | 功能描述:IC PWM CTRLR MULTIPHASE 40TQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:Robust Ripple Regulator™ (R³) 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,000 系列:- 应用:电源，ICERA E400，E450 输入电压:4.1 V ~ 5.5 V 输出数:10 输出电压:可编程 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:42-WFBGA，WLCSP 供应商设备封装:42-WLP 包装:带卷 (TR) |
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