- 您现在的位置：买卖IC网 > PDF目录80281 > LX2173CP (MICROSEMI CORP-ANALOG MIXED SIGNAL GROUP) 2.8 A SWITCHING REGULATOR, 115 kHz SWITCHING FREQ-MAX, PSFM5 PDF资料下载
参数资料
| 型号： | LX2173CP |
| 厂商： | MICROSEMI CORP-ANALOG MIXED SIGNAL GROUP |
| 元件分类： | 稳压器 |
| 英文描述： | 2.8 A SWITCHING REGULATOR, 115 kHz SWITCHING FREQ-MAX, PSFM5 |
| 封装： | PLASTIC, TO-220, 5 PIN |
| 文件页数： | 5/6页 |
| 文件大小： | 254K |
| 代理商： | LX2173CP |
1.25A HIGH-EFFICIENCY 100KHZ SWITCHING REGULATOR
LX2172/73
PRODUCT DA T ABOOK 1996/1997
5
Copyright 1998
Rev. 0.4
a 12/04
P RELIMINAR Y D AT A S HEET
THEOR Y OF OPERA TION
IC OPERATION
Referring to the block diagram, when V
IN is above the UVLO
start threshold the 2.3V UVLO comparator output switches to
low state, allowing Q1 to turn on upon receiving a clock pulse
from the internal 100kHz oscillator. Once Q1 is on, current in
the inductor ramps up. Inductor current is then sensed, and
amplified by a current sense amplifier and compared to a thresh-
old set by the output of the error amplifier minus the offset
voltage (V
OFS typically 0.9V).
This allows the PWM comparator
to reset the flip flop, causing Q1 to turn off. The oscillator then
sets the flip flop, and the operation repeats itself.
CURRENT LIMIT
Current limiting is performed by sensing the peak switch cur-
rent and turning Q1 off until the next clock cycle. When the
converter goes into current limit the error amplifier output goes
to the rail and sets a maximum limit on the current.
ERROR AMPLIFIER
The function of the error amplifier is to set a threshold voltage
for inductor peak current and control the switch duty cycle so
that the power supply output voltage is closely regulated. Regu-
lation is accomplished by sensing the output voltage and com-
paring it to the internal 1.27V bandgap reference. A compensa-
tion network is placed from the output of the amplifier to ground
for closed loop stability purposes, as well as a high d.c. gain for
tight regulation. The function of V
OFS is to keep Q1 of f without
requiring an error amplifier output to swing to ground level. It
is required the V
OL of the error amplifier is always less than the
offset at all times. The
transfer function between the error
amplifier output (V
C) and peak inductor current is therefore
given by:
V
C - VOFS = I P * G * R S
Where: I
P = Inductor peak current
G = Current sense gain (typically 6)
R
S = Internal sense r esistor
OSCILLATOR
The oscillator is designed to operate at 100kHz frequency. Its
function is to turn the switch Q1 on at a fixed 10s interval and
to provide a slope compensation for the feedback loop. Slope
compensation is required for fixed frequency continuous Cur-
rent Mode regulators operating above 50% duty cycle in order
to prevent loop instability. The SYNC input is a logic input that
allows easy synchronization to an external clock. Synchroniza-
tion is done such that the external clock terminates the cycle
before the internal oscillator sets the PWM latch again.
UNDER-VOLTAGE LOCKOUT
The 2.3V internal regulator is monitored as the input supply
ramps up, ensuring glitch-free operation.
EXTRA PINS ON 8-PIN DEVICE
The 8-pin versions of the LX217x have the emitters of the power
transistors brought out separately. Connecting these pins to
ground reduces errors due to ground pin voltage drops. The E
2
pin also allows the user to half the switch current limit if the pin
is left open. Note that the switch resistance will increase when
E
2 is open, so efficiency will decrease and heat dissipation will
increase, especially for currents over 300mA.
MICROPOWER SHUTDOWN
The LX2172/73 enter micropower shutdown mode when the V
C
pin is pulled below 0.15V. Supply current required for biassing
shutdown circuitry is less than 250A. The LX2173 has an EN-
ABLE pin which allows ultra-low micropower shutdown opera-
tion, consuming less than 10A.
O
B
SO
LETE
PRO
D
UCT
NOT
RECOMMENDED
FOR
NEW
DESIGNS
相关PDF资料 |
PDF描述 |
|---|---|
| LS4001-9RD6TB1 | 1-OUTPUT 100 W AC-DC PWR FACTOR CORR MODULE |
| LS5660-9RD8T | 2-OUTPUT 100 W AC-DC PWR FACTOR CORR MODULE |
| LT3652HVIDD#PBF | BATTERY CHARGE CONTROLLER, PDSO12 |
| LME1209SC | DC-DC REG PWR SUPPLY MODULE |
| LM3710XKBPX-232/NOPB | 2-CHANNEL POWER SUPPLY MANAGEMENT CKT, PBGA9 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LX2174 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Current-Mode SMPS Controller |
| LX21EVK01/NOPB | 功能描述:界面开发工具 DS92LX2121 EVAL BOARD RoHS:否 制造商:Bourns 产品:Evaluation Boards 类型:RS-485 工具用于评估:ADM3485E 接口类型:RS-485 工作电源电压:3.3 V |
| LX2201 | 制造商:MICROSEMI 制造商全称:Microsemi Corporation 功能描述:USB Li-Ion Battery Charger |
| LX2201CLQ | 功能描述:IC CHARGER BATT USB LI-ION 20MLP RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 其它有关文件:STC3100 View All Specifications 特色产品:STC3100 - Battery Monitor IC 标准包装:4,000 系列:- 功能:燃料，电量检测计/监控器 电池化学:锂离子（Li-Ion） 电源电压:2.7 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽） 供应商设备封装:8-MiniSO 包装:带卷 (TR) 其它名称:497-10526-2 |
| LX2201CLQ-TR | 制造商:Microsemi Corporation 功能描述:CHGR/CHRGR CONST I/V LI-ION 2A 4.2V 20MLPQ - Tape and Reel |
发布紧急采购，3分钟左右您将得到回复。