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参数资料
| 型号： | IRU3039CHTR |
| 厂商： | International Rectifier |
| 文件页数： | 6/22页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 20-MLPQ |
| 标准包装： | 1 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 400kHz |
| 占空比： | 88% |
| 电源电压： | 4.75 V ~ 20 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： | 0°C ~ 70°C |
| 封装/外壳： | 20-MLPQ |
| 包装： | 剪切带 (CT) |
| 其它名称： | *IRU3039CHTR IRU3039CHTRCT |
IRU3039(PbF)
The feedback voltage increases linearly as the injecting
current goes down. The injecting current drops to zero
when soft-start voltage is around 2V and the output volt-
age goes into steady state.
As shown in Figure 4, the positive pin of feedback UVLO
comparator is always higher than 0.4V, therefore, feed-
back UVLO is not functional during soft-start.
Shutdown
The converter can be shutdown by pulling the soft-start
pin below 0.4V. The control MOSFET turns off and the
synchronous MOSFET turns on during shutdown.
Over-Current Protection
Over-current protection is achieved with a cycle by cycle
scheme and it is performed by sensing current through
Output of UVLO
POR
3V
the R DS(ON) of low side MOSFET. As shown in Figure 5,
an external resistor (R SET ) is connected between OCSet
pin and the drain of low side MOSFET (Q2) and sets the
Soft-Start
Voltage
0V
? 2V
? 1V
current limit set point. The internal current source devel-
ops a voltage across R SET . When the low side switch is
turned on, the inductor current flows through the Q2 and
results a voltage which is given by:
Current flowing
into Fb pin
64uA
0uA
V OCSET = I OCSET × R SET -R DS(ON) × i L
---(1)
Voltage at negative input ? 1.6V
of Error Amp and Feedback
UVLO comparator
0.8V
I OCSET
IRU3039
Q1
Voltage at Fb pin
0V
0.8V
Osc
OCSet R SET
Q2
L1
V OUT
Figure 4 - Theoretical operational waveforms
during soft-start.
the output start-up time is the time period when soft-
start capacitor voltage increases from 1V to 2V. The start-
up time will be dependent on the size of the external
soft-start capacitor. The start-up time can be estimated
by:
20 μ A × T START /C SS = 2V-1V
For a given start up time, the soft-start capacitor can be
Figure 5 - Diagram of the over current sensing.
When voltage V OCSET is below zero, the current sensing
comparator flips and disables the oscillator. The high
side MOSFET is turned off and the low side MOSFET is
turned on until the inductor current reduces to below
current set value. The critical inductor current can be
calculated by setting:
V OCSET = I OCSET × R SET - R DS(ON) × I L = 0
estimated as:
C SS ? 20 μ A × T START /1V
I SET = I L(CRITICAL) =
R SET × I OCSET
R DS(ON)
---(2)
Internal Regulator
The regulator powers directly from Vcc and generates a
regulated voltage (6V @ 40mA). The output is protected
for short circuit. This voltage can be used for charge
pump circuitry as shown in Figure 1.
Supply Voltage Under-Voltage Lockout
The under-voltage lockout circuit assures that the
MOSFET driver outputs remain in the off state whenever
the supply voltage drops below set parameters. Lockout
occurs if Vc or Vcc fall below 3.4V and 4.4V respec-
tively. Normal operation resumes once Vc and Vcc rise
above the set values.
If the over-current condition is temporary and goes away
quickly, the IRU3039 will resume its normal operation.
If output is shorted or over-current condition persists,
the output voltage will keep going down until it is below
0.4V. Then the output under-voltage lock out comparator
goes high and turns off both MOSFETs. The operation
waveforms are shown in Figure 6.
6
www.irf.com
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| IRU3046 | 制造商:IRF 制造商全称:International Rectifier 功能描述:DUAL SYNCHRONOUS PWM CONTROLLER WITH CURRENT SHARING CIRCUITRY AND LDO CONTROLLER |
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| IRU3046CFTR | 功能描述:IC REG CTRLR BUCK PWM VM 24TSSOP 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:75 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.3 V ~ 13.5 V 降压:是 升压:是 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:0°C ~ 70°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:管件 产品目录页面:1051 (CN2011-ZH PDF) 其它名称:296-2543-5 |
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