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参数资料
| 型号： | LX1673-06CLQT |
| 厂商： | MICROSEMI CORP-ANALOG MIXED SIGNAL GROUP |
| 元件分类： | 稳压器 |
| 英文描述： | 1 A SWITCHING CONTROLLER, 690 kHz SWITCHING FREQ-MAX, PQCC20 |
| 封装： | PLASTIC, MLPQ-20 |
| 文件页数： | 15/15页 |
| 文件大小： | 302K |
| 代理商： | LX1673-06CLQT |
Microsemi
Integrated Products
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 9
Copyright
2000
Rev. 0.2j, 2002-07-17
WWW
.M
ic
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sem
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.COM
LX1673
High Frequency PWM Regulator
PRELIMINARY
INTEGR A T E D
PR ODU C T S
THEORY O F OP ERA T ION
GENERAL DESCRIPTION
The LX1673 is a voltage-mode pulse-width modulation
controller integrated circuit. The internal oscillator and ramp
generator frequency is fixed to 300KHz, 600KHz, or 900KHz.
The device has external compensation, for more flexibility of
output current magnitude.
UNDER VOLTAGE LOCKOUT (UVLO)
At power up, the LX1673 monitors the supply voltage for
VCC, VCCL, LDVCC and VC1 (there is no requirement for
sequencing the supplies). Before all supplies reach their under-
voltage lock-out (UVLO) thresholds, the soft-start (SS) pin is
held low to prevent soft-start from beginning, the oscillator is
disabled and all MOSFETs are held off. There is an internal
delay that will filter out transients less that 1.5uSec.
SOFT-START
Once the supplies are above the UVLO threshold, the soft-start
capacitor begins to be charged by the reference through a 20k
internal resistor. The capacitor voltage at the SS pin rises as a
simple RC circuit.
The SS pin is connected to the error
amplifier’s non-inverting input that controls the output voltage.
The output voltage will follow the SS pin voltage if sufficient
charging current is provided to the output capacitor.
The simple RC soft-start allows the output to rise faster at the
beginning and slower at the end of the soft-start interval. Thus,
the required charging current into the output capacitor is less at
the end of the soft-start interval. A comparator monitors the SS
pin voltage and indicates the end of soft-start when SS pin
voltage reaches 95% of VREF.
OVER-CURRENT PROTECTION (OCP) AND HICCUP
The LX1673 uses the RDS(ON) of the upper MOSFET, together
with a resistor (RSET) to set the actual current limit point. The
current sense comparator senses the MOSFET current 350nS
after the top MOSFET is switched on in order to reduce
inaccuracies due to ringing. A current source supplies a current
(ISET), whose magnitude is 50A. The set resistor RSET is
selected to set the current limit for the application. RSET and VS
should be connected directly at the upper MOSFET drain and
source to get an accurate measurement across the low resistance
RDS(ON).
When the sensed voltage across RDS(ON) plus the set resistor
exceeds the 300mV, VTRIP threshold, the OCP comparator outputs
a signal to reset the PWM latch and to start hiccup mode. The
soft-start capacitor (CSS) is discharged slowly (10 times slower
than when being charged up by RSS). When the voltage on the SS
pin reaches a 0.1V threshold, hiccup finishes and the circuit soft-
starts again. During hiccup both MOSFETs are held off.
Hiccup is disabled during the soft-start interval, allowing the
circuit to start up with maximum current. If the rate of rise of the
output voltage is too fast, the required charging current to the
output capacitor may be higher than the limit-current. In this case,
the peak MOSFET current is regulated to the limit-current by the
current-sense comparator. If the MOSFET current still reaches its
limit after the soft-start finishes, the hiccup is triggered again.
When the output has a short circuit the hiccup circuit ensures that
the average heat generation in both MOSFETs and the average
current is much less than in normal operation,.
Over-current protection can also be implemented using a sense
resistor, instead of using the RDS(ON) of the upper MOSFET, for
greater set-point accuracy.
OSCILLATOR FREQUENCY
An internal oscillator sets the switching frequency at 300kHz,
600kHz, or 900kHz.
AA
PP
LL
IICC
AA
TT
IIOO
NN
SS
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LX1673-06CLQ-TR | 制造商:Microsemi Corporation 功能描述:VOLT MODE PWM CNTRLR 0.8V TO 5.5V 1A 20MLPQ - Tape and Reel |
| LX1673-06CPW | 功能描述:IC REG DL BCK/LINEAR 20TSSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式 系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（3），线性（LDO）（2） 功能:任何功能 输出数:5 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器 电压/电流 - 输出 2:控制器 电压/电流 - 输出 3:控制器 带 LED 驱动器:无 带监控器:无 带序列发生器:是 电源电压:5.6 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* |
| LX1673-06CPW-TR | 制造商:Microsemi Corporation 功能描述:VOLT MODE PWM CNTRLR 0.8V TO 5.5V 1A 20TSSOP - Tape and Reel |
| LX1673-09CLQ | 功能描述:IC REG DL BCK/LINEAR SYNC 20MLPQ RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式 系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（2），线性（LDO）（1） 功能:任何功能 输出数:3 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器 电压/电流 - 输出 2:控制器 电压/电流 - 输出 3:控制器 带 LED 驱动器:无 带监控器:无 带序列发生器:是 电源电压:4.5 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:28-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:* 包装:带卷 (TR) 其它名称:ISL6402IVZ-TTR |
| LX1673-09CLQ-TR | 制造商:Microsemi Corporation 功能描述:VOLT MODE PWM CNTRLR 0.8V TO 5.5V 1A 20MLPQ - Tape and Reel |
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