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| 型号： | IRU3073CQTR |
| 厂商： | International Rectifier |
| 文件页数： | 5/21页 |
| 文件大小： | 236K |
| 描述： | IC REG DL BCK/LINEAR 16-QSOP |
| 标准包装： | 1 |
| 拓扑： | 降压（降压）同步（1），线性（LDO）（1） |
| 功能： | 任何功能 |
| 输出数： | 2 |
| 频率 - 开关： | 210kHz ~ 400kHz |
| 电压/电流 - 输出 1： | 控制器 |
| 电压/电流 - 输出 2： | 0.8 V ~ 22.5 V，65mA |
| 带 LED 驱动器： | 无 |
| 带监控器： | 无 |
| 带序列发生器： | 是 |
| 电源电压： | 4.4 V ~ 25 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | * |
| 包装： | 剪切带 (CT) |
| 其它名称： | *IRU3073CQTR IRU3073CQCT |
IRU3073
5
Rev. 1.0
09/17/03
www.irf.com
THEORY OF OPERATION
Introduction
The IRU3073 is designed for a two output application
and it includes one synchronous buck controller and a
linear regulator controller. The PWM section is a fixed
frequency, voltage mode and consists of a precision ref-
erence voltage, an uncommitted error amplifier, an inter-
nal oscillator, a PWM comparator, an internal regulator,
a comparator for current limit, gate drivers, soft-start and
shutdown circuits (see Block Diagram).
The output voltage of the synchronous converter is set
and controlled by the output of the error amplifier; this is
the amplified error signal from the sensed output voltage
and the voltage on non-inverting input of error amplifier(VP).
This voltage is compared to a fixed frequency linear
sawtooth ramp and generates fixed frequency pulses of
variable duty-cycle, which drives the two N-channel ex-
ternal MOSFETs.
The timing of the IC is provided through an internal oscil-
lator circuit which uses on-chip capacitor. The oscilla-
tion frequency is programmable between 200KHz to
400KHz by using an external resistor. Figure 14 shows
switching frequency vs. external resistor (Rt).
Soft-Start
The IRU3073 has a programmable soft-start to control
the output voltage rise and limit the current surge at the
start-up. To ensure correct start-up, the soft-start se-
quence initiates when the input supplies rise above their
threshold and generates the Power On Reset (POR) sig-
nal. Soft-start function operates by sourcing an internal
current to charge an external capacitor to about 3V. Ini-
tially, the soft-start function clamps the E/As output of
the PWM converter and disables the short circuit pro-
tection. During the power up of the buck converter, the
output starts at zero and voltage at Fb1 is below 0.4V.
The feedback UVLO is disabled during this time by in-
jecting a current (64mA) into the Fb1. This generates a
voltage about 1.6V (64mA325K) across the negative
input of E/A and positive input of the feedback UVLO
comparator (see Fig3).
Figure 3 - IRU3073 soft-start diagram.
The magnitude of this current is inversely proportional to
the voltage at soft-start pin.
The 20mA current source starts to charge up the exter-
nal capacitor. In the mean time, the soft-start voltage
ramps up, the current flowing into Fb1 pin starts to de-
crease linearly and so does the voltage at the positive
pin of feedback UVLO comparator and the voltage nega-
tive input of E/A.
When the soft-start capacitor is around 1V, the current
flowing into the Fb1 pin is approximately 32mA. The volt-
age at the positive input of the E/A is approximately:
The E/A will start to operate and the output voltage starts
to increase. As the soft-start capacitor voltage contin-
ues to go up, the current flowing into the Fb1 pin will
keep decreasing. Because the voltage at pin of E/A is
regulated to reference voltage 0.8V, the voltage at the
Fb1 is:
32mA325K = 0.8V
VFB1 = 0.8-25K3(Injected Current)
20uA
64uA
Max
POR
Error Amp
64uA325K=1.6V
When SS=0
POR
0.4V
Feeback
UVLO Comp
SS/SD
Fb1
Comp
25K
0.8V
25K
HDrv
LDrv
3V
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| IRU3137 | 制造商:IRF 制造商全称:International Rectifier 功能描述:8-PIN SYNCHRONOUS PWM CONTROLLER |
| IRU3137CS | 制造商:IRF 制造商全称:International Rectifier 功能描述:8-PIN SYNCHRONOUS PWM CONTROLLER |
| IRU3137CSTR | 功能描述:IC REG CTRLR BUCK PWM VM 8-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| IRU3137CSTRPBF | 功能描述:IC REG CTRLR BUCK PWM VM 8-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| IRU3138 | 制造商:IRF 制造商全称:International Rectifier 功能描述:SYNCHRONOUS PWM CONTROLLER FOR TERMINATION POWER SUPPLY APPLICATIONS |
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