- 您现在的位置：买卖IC网 > PDF目录20625 > LT1939EDD#PBF (Linear Technology)IC REG DL BUCK/LINEAR 12DFN PDF资料下载
参数资料
| 型号： | LT1939EDD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/24页 |
| 文件大小： | 349K |
| 描述： | IC REG DL BUCK/LINEAR 12DFN |
| 标准包装： | 121 |
| 拓扑： | 降压（降压）（1），线性（LDO）（1） |
| 功能： | 任何功能 |
| 输出数： | 2 |
| 频率 - 开关： | 500kHz ~ 2.4MHz |
| 电压/电流 - 输出 1： | 0.8 V ~ 24.25 V，2A |
| 电压/电流 - 输出 2： | 0.8 V ~ 24.25 V，1A |
| 带 LED 驱动器： | 无 |
| 带监控器： | 无 |
| 带序列发生器： | 无 |
| 电源电压： | 3 V ~ 25 V |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 12-WFDFN 裸露焊盘 |
| 供应商设备封装： | 12-DFN |
| 包装： | 管件 |
LT1939
11
1939f
APPLICATIONS INFORMATION
Table 1. Ef ciency and Size Comparisons for Different R
RT/SYNC
Values, 3.3V Output
FREQUENCY
R
T
/SYNC
EFFICIENCY
V
IN(MAX)
L
C
C + L AREA
(mm
2
)
2.5MHz
15k
73.6
12
1?/DIV>
10?/DIV>
24
2.0MHz
20k
81.5
14
1.5?/DIV>
10?/DIV>
24
1.5MHz
24.9k
84.5
18
2.2?/DIV>
10?/DIV>
24
1.0MHz
40.2k
87.3
25
3.3?/DIV>
22?/DIV>
34
500kHz
90.9k
88.9
25
4.7?/DIV>
47?/DIV>
40
The following example along with the data in Table 1
illustrates the tradeoffs of switch frequency selection.
Example.
V
IN
= 25V, V
OUT1
= 3.3V, I
OUT1
= 2A,
Temperature = 0癈 to 85癈
t
ON(MIN)
= 185ns (85癈 from Typical Characteris-
tics graph), V
D
= 0.6V, V
SW
= 0.4V (85癈)
MaxFrequency=
3.3+0.6
250.4+
0.6
"
1
185
ns
~835kHz
R
T
/SYNC ~ 49.9k
Frequency E 820kHz
Input Voltage Range
Once the switching frequency has been determined, the
input voltage range of the regulator can be determined.
The minimum input voltage is determined by either the
LT1939s minimum operating voltage of ~2.8V or by its
maximum duty cycle. The duty cycle is the fraction of time
that the internal switch is on during a clock cycle. The
maximum duty cycle can be determined from the clock
frequency and the minimum off time from the typical
characteristics graph.
This leads to a minimum input voltage of:
V
IN(MIN)
=
V
OUT1
+V
D
DC
MA
X
V
D
+V
SW
where V
SW
is the voltage drop of the internal switch,
and
DC
MAX
= 1 t
OFF(MIN)
" Frequency.
Figure 3 shows a typical graph of minimum input voltage
vs load current for 3.3V and 5V applications.
The maximum input voltage is determined by the absolute
maximum ratings of the V
IN
and BST pins and by the
frequency and minimum duty cycle.
The minimum duty cycle is de ned as:
DC
MIN
= t
ON(MIN)
" Frequency
Maximum input voltage as:
V
IN(MAX)
=
V
OUT1
+V
D
DC
MI
N
V
D
+V
SW
Figure 3. Minimum Input Voltage vs Load Current
LOAD CURRENT (A)
0
3
4
5
1.0
1.6 1.8
1939 F03
2
0.2 0.4 0.6 0.8
1.4
1.2
6
7
8
2.0
V
OUT1
= 5V START-UP
V
OUT1
= 5V RUNNING
V
OUT1
= 3.3V START-UP
V
OUT1
= 3.3V RUNNING
F
SW
= 1MHz
L = 3.3糎
相关PDF资料 |
PDF描述 |
|---|---|
| T95Y685M025LZAL | CAP TANT 6.8UF 25V 20% 2910 |
| V48C12H75BG2 | CONVERTER MOD DC/DC 12V 75W |
| ISL6612ACBZAR5214 | IC MOSFET DRVR SYNC BUCK 8-SOIC |
| CS5463-ISZR | IC ENERGY METERING 1PHASE 24SSOP |
| 591D227X9010R2T20H | CAP TANT 220UF 10V 10% 2824 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1939EDD-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Monolithic 2A Step-Down Regulator Plus Linear Regulator/Controller |
| LT1939IDD#PBF | 功能描述:IC REG DL BUCK/LINEAR 12DFN 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（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:* |
| LT1939IDD#TRPBF | 功能描述:IC REG DL BUCK/LINEAR 12DFN 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（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:* |
| LT1939IDD-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Monolithic 2A Step-Down Regulator Plus Linear Regulator/Controller |
| LT1939IDD-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Monolithic 2A Step-Down Regulator Plus Linear Regulator/Controller |
发布紧急采购，3分钟左右您将得到回复。