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参数资料
| 型号： | LT1534C |
| 厂商： | Linear Technology Corporation |
| 元件分类： | 基准电压源/电流源 |
| 英文描述： | RADIATION HARDENED HIGH EFFICIENCY, 5 AMP SWITCHING REGULATORS |
| 中文描述： | 抗辐射高效，5安培开关稳压器 |
| 文件页数： | 8/16页 |
| 文件大小： | 222K |
| 代理商： | LT1534C |
8
LT1534/LT1534-1
The negative feedback amplifier allows for direct regula-
tion 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
R
CSL
. The two control loops are combined internally to
provide a smooth transition from current slew control to
voltage slew control.
OPERATIOU
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 LT1534. 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.
APPLICATIO
S I
FOR
ATIO
U
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 LT1534 provides control over two of the more impor-
tant variables for controlling EMI with switching inductive
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.
It is beyond the scope of this data sheet to get into EMI
fundamentals. AN70 contains much information concern-
ing noise in switching regulators and should be consulted.
W
U
U
Oscillator Frequency
The oscillator determines the switching frequency and
therefore the fundamental positioning of all harmonics.
The use of good quality external components is important
to ensure oscillator frequency stability. The oscillator is a
sawtooth design. A current defined by external resistor R
T
is used to charge and discharge the capacitor C
T
. The
discharge rate is approximately ten times the charge rate.
By allowing the user to have control over both compo-
nents, trimming of oscillator frequency can be more easily
achieved.
The external capacitance C
T
is chosen by:
C
T(nF)
= 2180/[f
OSC(kHz)
R
T(k
)
]
where f
OSC
is the desired oscillator frequency in kHz.
For R
T
equal to 16.9k, this simplifies to:
C
T(nF)
= 129/f
OSC(kHz)
(e.g., C
T
= 1.29nF for f
OSC
= 100kHz)
A good quality temperature stable capacitor should be
chosen.
Nominally R
T
should be 16.9k. Since it sets up current, its
temperature coefficient should be selected to compliment
the capacitor. Ideally, both should have low temperature
coefficients.
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| LT1534CS | 功能描述:IC REG BOOST ADJ 2A 16SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT1534CS#PBF | 功能描述:IC REG BOOST ADJ 2A 16SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT1534CS#TR | 功能描述:IC REG BOOST ADJ 2A 16SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
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