- 您现在的位置：买卖IC网 > PDF目录97995 > L5994A (STMICROELECTRONICS) 1 A DUAL SWITCHING CONTROLLER, 345 kHz SWITCHING FREQ-MAX, PQFP32 PDF资料下载
参数资料
| 型号： | L5994A |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 稳压器 |
| 英文描述： | 1 A DUAL SWITCHING CONTROLLER, 345 kHz SWITCHING FREQ-MAX, PQFP32 |
| 封装： | TQFP-32 |
| 文件页数： | 7/26页 |
| 文件大小： | 322K |
| 代理商： | L5994A |
Obsolete
Product(s)
- Obsolete
Product(s)
15/26
L5994 - L5994A
+3.3V Inductor
To define the inductor, it is necessary to determine firstly the inductance value. Its minimum value is given by:
and a value L3 > L3MIN should be selected. Core geometry selection is connected to the requirements of the
specific application in terms of space utilization and other practical issues like ease of mounting, availability and
so on. As to the material, the choice should be directed towards ferrite, molypermalloy or KoolM
, to achieve
high efficiency. These materials provide low core losses (ferrite in particular), so that the design can be concen-
trated on preventing saturation and limiting copper losses. Saturation must be avoided even at maximum peak
current:
To limit copper losses, the winding DC resistance, RL, should be as low as possible (in the range of m). AC
losses can usually be neglected. A practical criterion to minimize DC resistance could be to use the largest wire
that fits the selected core.
Anyway the best solution, whenever possible, is to use an off-the-shelf inductor which meets the requirements
in terms of inductance and maximum DC current. Nowadays there is a broad range of products offered by man-
ufacturer, also for surface mount assemblies.
+5.1V Transformer
The primary winding carries the secondary power as well, thus the total primary average current is:
where VDRLIN is the voltage generated during the recirculation of the primary and fed into the input of the +12V
linear regulator. The turns ratio 1:n of the transformer is chosen so that VDRLIN is above 13V. To reduce the
turns ratio in order to minimize stray parameters, the secondary is referred to the 5.1V output, and therefore the
minimum value is given by:
where Vf is the forward drop across the rectifier (assume 1V to be conservative). Make sure the secondary is
connected with the proper polarity (see fig. 4). The minimum primary inductance value can be expressed as:
where RF, to get positive values for L5PMIN, must satisfy the inequality:
and where VIN can be either VINMIN or VINMAX, whichever gives the higher value for L5PMIN. With a primary in-
ductance L5P > L5PMIN the primary peak current, which must not saturate the magnetic core, will be:
As to the transformer realization, the considerations regarding to the +3.3V inductor can be here repeated.
L
3M IN
3.3
V
IN M AX
3.3
–
()
–
V
IN MAX
f
SW
I
OUT3
RF
---------------------------------------------------------------------
=
I
L3PK
I
OUT3
3.3
V
IN M AX
3.3
–
()
2f
SW
L
3
V
IN M AX
------------------------------------------------------
+
=
I
TO T5
I
OU T 5
V
IN LIN
I
OUT12
5.1
-----------------------------------------
+
=
η
MIN
V
IN LIN
5.1
–
V
f
+
5.1
--------------------------------------------
=
L
5pm in
3
4
---
5.1
V
IN
5.1
–
()
2
V
IN
f
SW
I
TO T5
RF
V
IN
5.1
–
() η
–
V
IN
I
OUT12
[]
---------------------------------------------------------------------------------------------------------------------------------------------
=
RF
η V
IN
I
OUT12
I
TOT5
V
IN
5.1
–
()
------------------------------------------------
>
I
5PK
I
5TO T
5.1
V
IN MA X
5.1
–
()
2f
SW
L
5P
V
IN M AX
----------------------------------------------------------
η I
OUT12
++
=
相关PDF资料 |
PDF描述 |
|---|---|
| L5994 | 1 A DUAL SWITCHING CONTROLLER, 345 kHz SWITCHING FREQ-MAX, PQFP32 |
| L6206PD013TR | STEPPER MOTOR CONTROLLER, 5.6 A, PDSO36 |
| L6207PD013TR | STEPPER MOTOR CONTROLLER, 5.6 A, PDSO36 |
| L6219DSA | STEPPER MOTOR CONTROLLER, 1 A, PDSO24 |
| L6228PDTR | STEPPER MOTOR CONTROLLER, 2.8 A, PDSO36 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| L5995 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Current-Mode SMPS Controller |
| L5996 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:5 BIT DYNAMIC DAC CONTROLLER FOR MOBILE CPU |
| L-59BL/1EGW | 制造商:Kingbright Corporation 功能描述: 制造商:Kingbright Corporation 功能描述:LED 5MM RED/GREEN 40MCD/60MCD 制造商:Kingbright Corporation 功能描述:LED, 5MM, RED/GREEN, 40MCD/60MCD 制造商:Kingbright Corporation 功能描述:LED, 5MM, RED/GREEN, 40MCD/60MCD, LED Colour:Red, Green, Height:7.24mm, Width:7. 制造商:Kingbright Corporation 功能描述:Red/grn r/a cbi,5mm,L-59BL/1EGW |
| L-59BL/1EYW | 制造商:Kingbright Corporation 功能描述: 制造商:Kingbright Corporation 功能描述:LED 5MM RED/YELLOW 40MCD/40MCD 制造商:Kingbright Corporation 功能描述:LED, 5MM, RED/YELLOW, 40MCD/40MCD 制造商:Kingbright Corporation 功能描述:LED, 5MM, RED/YELLOW, 40MCD/40MCD, LED Colour:Red, Yellow, Height:7.24mm, Width: |
| L-59BL/1GEW | 制造商:Kingbright Corporation 功能描述: |
发布紧急采购，3分钟左右您将得到回复。