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参数资料
| 型号： | LT1943EFE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 15/20页 |
| 文件大小： | 0K |
| 描述： | IC REG SW QUAD TFT LCD 28-TSSOP |
| 标准包装： | 2,000 |
| 应用： | 转换器，TFT，LCD |
| 输入电压： | 4.5 V ~ 22 V |
| 输出数： | 4 |
| 输出电压： | 1.25 V ~ 40 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SOIC（0.173"，4.40mm 宽）裸露焊盘 |
| 供应商设备封装： | 28-TSSOP 裸露焊盘 |
| 包装： | 带卷 (TR) |
LT1943
OPERATIO
DC =
| V OUT |
V IN + | V OUT |
Output Capacitor Selection
Use low ESR (equivalent series resistance) capacitors at
The LT1943 can still be used in applications where the duty
cycle, as calculated above, is above the maximum. How-
ever, the part must be operated in discontinuous mode so
that the actual duty cycle is reduced.
Inductor Selection
Several inductors that work well with the LT1943 regulator
are listed in Table 4. Besides these, many other inductors
will work. Consult each manufacturer for detailed informa-
tion and for their entire selection of related parts. Use
ferrite core inductors to obtain the best efficiency, as core
losses at frequencies above 1MHz are much lower for
ferrite cores than for powdered-iron units. A 10 μ H to 22 μ H
inductor will be the best choice for most LT1943 step-up
and charge pump designs. Choose an inductor that can
carry the entire switch current without saturating. For
inverting and SEPIC regulators, a coupled inductor, or two
separate inductors is an option. When using coupled
inductors, choose one that can handle at least the switch
current without saturating. If using uncoupled inductors,
each inductor need only handle approximately one-half of
the total switch current. A 4.7 μ H to 15 μ H coupled inductor
or two 10 μ H to 22 μ H uncoupled inductors will usually be
the best choice for most LT1943 inverting and SEPIC
designs.
Table 4. Inductors.
Part Number Value ( μ H) I RMS (A) DCR ( ? ) Height (mm)
Coiltronics
the output to minimize the output ripple voltage. Multilayer
ceramic capacitors are an excellent choice, as they have an
extremely low ESR and are available in very small pack-
ages. X7R dielectrics are preferred, followed by X5R, as
these materials retain their capacitance over wide voltage
and temperature ranges. A 10 μ F to 22 μ F output capacitor
is sufficient for most LT1943 applications. Even less
capacitance is required for outputs with |V OUT | > 20V or
| I OUT | < 100mA. Solid tantalum or OS-CON capacitors will
also work, but they will occupy more board area and will
have a higher ESR than a ceramic capacitor. Always use a
capacitor with a sufficient voltage rating.
Diode Selection
A Schottky diode is recommended for use with the LT1943
switcher 2 and switcher 4. The Schottky diode for switcher
3 is integrated inside the LT1943. Choose diodes for
switcher 2 and switcher 4 rated to handle an average
current greater than the load current and rated to handle
the maximum diode voltage. The average diode current in
the step-up, SEPIC, and inverting configurations is equal
to the load current. Each of the two diodes in the charge
pump configurations carries an average diode current
equal to the load current. The maximum diode voltage in
the step-up and charge pump configurations is equal to
|V OUT |. The maximum diode voltage in the SEPIC and
inverting configurations is V IN + |V OUT |.
Input Capacitor Selection
TP3-4R7
TP4-100
4.7
10
1.5
1.5
0.181
0.146
2.2
3.0
Bypass the input of the LT1943 circuit with a 4.7 μ F or
higher ceramic capacitor of X7R or X5R type. A lower value
Sumida
or a less expensive Y5V type will work if there is additional
CD73-100
CDRH5D18-6R2
CDRH4D28-100
CDRH4D28-100
Coilcraft
DO3314-103
1008PS-103
10
6.2
10
10
10
10
1.44
1.4
1.3
1.0
0.8
0.78
0.080
0.071
0.048
0.095
0.520
0.920
3.5
2.0
3.0
3.0
1.4
2.8
bypassing provided by bulk electrolytic capacitors or if the
input source impedance is low. The following paragraphs
describe the input capacitor considerations in more detail.
Step-down regulators draw current from the input supply
in pulses with very fast rise and fall times. The input
capacitor is required to reduce the resulting voltage ripple
at the LT1943 input and to force this switching current into
a tight local loop, minimizing EMI. The input capacitor
1943fa
15
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| LT1944-1EMS | 功能描述:IC REG BST ADJ 0.1A/175MA 10MSOP 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:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LT1944-1EMS#PBF | 功能描述:IC REG BST ADJ 0.1A/175MA 10MSOP 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:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 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:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
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