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| 型号： | LT1533IS#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 7/20页 |
| 文件大小： | 0K |
| 描述： | IC REG PUSH-PLL CTRLR ISO 16SOIC |
| 标准包装： | 50 |
| 类型： | 推挽式控制器，隔离式 |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.3 V ~ 30 V |
| 输入电压： | 2.7 V ~ 23 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 200kHz ~ 250kHz |
| 电流 - 输出： | 1A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 100°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 16-SOIC |
| 产品目录页面： | 1327 (CN2011-ZH PDF) |
LT1533
OPERATIO
Output regulation is obtained using the error amp to set
the switch current trip point. The error amp is a transcon-
ductance amplifier that integrates the difference between
the feedback output voltage and an internal 1.25V refer-
ence. The output of the error amp adjusts the switch
current trip point to provide the required load current at
the desired regulated output voltage. This method of
controlling current rather than voltage provides faster
input transient response, cycle by cycle current limiting
for better output switch protection and greater ease in
compensating the feedback loop.
The V C pin serves three different purposes. It is used for
loop compensation, current limit adjustment and soft
starting. During normal operation the V C voltage will be
between 0.2V and 1.33V. An external clamp may be used
for lowering the current limit. A capacitor coupled to an
external clamp can be used for soft starting.
The negative voltage feedback amplifier allows for direct
regulation of negative output voltages. The voltage on the
NFB pin gets amplified by a gain of – 0.5 and driven onto
the FB input, i.e., the NFB pin regulates to – 2.5V while the
amplifier output internally drives the FB pin to 1.25V as in
normal operation. The negative feedback amplifier input
impedance is 100k (typ) referred to ground.
Slew Control
Control of output voltage and current slew rates is done via
two feedback loops. One loop controls the output switch
collector voltage dV/dt and the other loop controls the
emitter current dI/dt. Output slew control is achieved by
comparing the currents generated by these two slewing
events to currents created by external resistors R VSL and
APPLICATIO N S I N FOR M ATIO N
Reducing EMI from switching power supplies has tradi-
tionally invoked fear in designers. Many switchers are
designed solely on efficiency and as such produce wave-
forms filled with high frequency harmonics that then
propagate through the rest of the power supply.
The LT1533 provides control over two of the more impor-
R CSL . The two control loops are combined internally to
provide a smooth transition from current slew control to
voltage slew control.
Internal Regulator
Most of the control circuitry operates from an internal 2.4V
low dropout regulator that is powered from V IN . The
internal low dropout design allows V IN to vary from 2.7V
to 23V with virtually no change in device performance.
When the part is put into shutdown, the internal regulator
is turned off, leaving only a small (12 μ A typ) current drain
from V IN .
Protection Features
There are three modes of protection in the LT1533. The
first is overcurrent limit. This is achieved via the clamping
action of the V C pin. The second is thermal shutdown that
disables both output drivers and pulls the V C pin low in the
event of excessive chip temperature. The third is under-
voltage lockout that also disables both outputs
and pulls the V C pin low whenever V IN drops below 2.5V.
50% Duty Cycle Mode
Since the LT1533 has dual out-of-phase outputs, it is ideal
for driving push-pull transformers. For simple DC trans-
former applications, the part can be forced into a 50% duty
cycle mode using the DUTY pin. Grounding the DUTY pin
will override the internal control circuitry and force the
outputs to switch with a 50% duty cycle at one-half the
oscillator frequency. Slew control also applies in the 50%
duty cycle mode.
loads: switch voltage slew rate and switch current slew
rate. The use of this part will reduce noise and EMI over
conventional switch mode controllers. Because these
variables are under control, a supply built with this part will
exhibit far less tendency to create EMI and less chance of
wandering into problems during production.
tant variables for controlling EMI with switching inductive
7
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相关代理商/技术参数 |
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|---|---|
| LT1534 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Ultralow Noise 2A Switching Regulators |
| LT1534-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Ultralow Noise 2A Switching Regulators |
| LT-1534-501-024 | 制造商:Carling Technologies 功能描述:LT-SERIES TOGGLE SWITCH - Bulk |
| LT-1534-510-012 | 制造商:Carling Technologies 功能描述:LT-SERIES TOGGLE SWITCH - Bulk |
| LT-1534-510-024 | 制造商:Carling Technologies 功能描述:LT-SERIES TOGGLE SWITCH - Bulk |
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