LA5757TP [SANYO]
Switching Regulator; 开关稳压器
| 型号： | LA5757TP |
| 厂家： | 
SANYO SEMICON DEVICE |
| 描述： | Switching Regulator |
| 文件： | 总6页 (文件大小：74K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Ordering number : ENA1439
Monolithic Linear IC
Separately-excited Step-down
Switching Regulator (Variable Type)
LA5757TP
Overview
The LA5757TP is a separately-excited step-down switching regulator (variable type).
Features
• Output smoothing condenser can use a Low ESR condenser for the reliability improvement
• High efficiency
• Four external parts
• Time-base generator (300kHz) incorporated
• Current limiter incorporated
• Thermal shutdown circuit incorporated
• Soft start circuit incorporated
Specifications
Maximum Ratings at Ta = 25°C
Parameter
Input voltage
Symbol
Conditions
Ratings
Unit
V
V
I
34
1.5
IN max
max
Output current
A
O
SW pin application reverse
Allowable power dissipation
Operating temperature
Storage temperature
V
-1
V
SW
Pd max
Topr
Mounted on a specified board*
1.1
W
°C
°C
-30 to +125
-40 to +150
Tstg
* Specified board: 114.3mm × 76.1mm × 1.6mm, glass epoxy board.
Recommended Operating Conditions at Ta = 25°C
Parameter
Symbol
Conditions
Ratings
Unit
V
Input voltage range
V
4.5 to 32
IN
Any and all SANYO Semiconductor Co.,Ltd. products described or contained herein are, with regard to
"standard application", intended for the use as general electronics equipment (home appliances, AV equipment,
communication device, office equipment, industrial equipment etc.). The products mentioned herein shall not be
intended for use for any "special application" (medical equipment whose purpose is to sustain life, aerospace
instrument, nuclear control device, burning appliances, transportation machine, traffic signal system, safety
equipment etc.) that shall require extremely high level of reliability and can directly threaten human lives in case
of failure or malfunction of the product or may cause harm to human bodies, nor shall they grant any guarantee
thereof. If you should intend to use our products for applications outside the standard applications of our
customer who is considering such use and/or outside the scope of our intended standard applications, please
consult with us prior to the intended use. If there is no consultation or inquiry before the intended use, our
customer shall be solely responsible for the use.
Specifications of any and all SANYO Semiconductor Co.,Ltd. products described or contained herein stipulate
the performance, characteristics, and functions of the described products in the independent state, and are not
guarantees of the performance, characteristics, and functions of the described products as mounted in the
customer's products or equipment. To verify symptoms and states that cannot be evaluated in an independent
device, the customer should always evaluate and test devices mounted in the customer
's products or
equipment.
40809 MS 20090326-S00004 No.A1439-1/6
LA5757TP
Electrical Characteristics at Ta = 25°C, V = 5V
O
Ratings
typ
Parameter
Symbol
OS
Conditions
Unit
min
max
1.280
Reference voltage
V
η
f
1.230
1.255
83
V
%
Efficiency
Switching frequency
Line regulation
V
= 15V, I = 1.0A
240
300
40
360
100
30
kHz
mV
mV
mV/°C
dB
IN
IN
IN
O
∆V LINE
V
V
= 8 to 20V, I =1.0A
O
O
Load regulation
∆V LOAD
= 15V, I = 0.5 to 1.5A
O
10
O
Output voltage temperature coefficient
Ripple attenuation factor
Current limiter operating voltage
∆V /∆Ta
Designed target value*
f = 100 to 120Hz
±0.5
45
O
RREJ
I
V
= 15V
1.6
A
S
IN
Thermal shutdown operating temperature TSD
Thermal shutdown hysteresis width ∆TSD
Designed target value*
Designed target value*
165
15
°C
°C
* Designed target value: No measurement made.
Package Dimensions
unit : mm (typ)
3332
Pd max -- Ta
1.4
Specified board: 114.3×76.1×1.6mm3
glass epoxy board.
6.5
5.0
1.2
1.1
1
2.3
With specified board
0.5
0.8
0.6
0.4
0.6
0.2
1.2
0.22
0.2
0
(0.65)
1.3
0.5
0.5
1
2
5
--30--20
0
20
40
60
80
100
120
140
Ambient temperature, Ta -- °C
SANYO : TP5HFA
Pin Assignment
(1)V
(2)SW
(3)GND (4)V
(5)SS
OS
IN
OUT
No.A0951-2/5
LA5757TP
Block Diagram
V
1
2
SW
OUT
IN
Constnt
Current
Circuit
Reg.
OCP
OSC
RESET
DRIVE
TSD
Comp.
2
V
OS
Amp.
ON/OFF Comp.
0.4V
VREF
5
3
SS
GND
Application Circuit Example
L1
V
SW
OUT
IN
LA5757TP
C2
D1
C1
V
OS
R2
R1
SS
GND
C3
Notes: C3 is for the soft start function. Delete C3 and keep the SS pin open when the soft function is not necessary.
Description of Functional Settings
1. Calculation equation to set the output voltage
This IC controls the switching output so that the V
The equation to set the output voltage is as follows:
pin voltage becomes 1.255V (typ).
OS
R2
R1
V
O
= 1+
× 1.255V(typ)
The V
OS
pin has the inrush current of 1µA (typ). Therefore, the error becomes larger when R1 and R2 resistance
values are large.
No.A0951-3/5
LA5757TP
2. Start delay function
The SS pin has the internally-connected 10µA (typ) constant-current supply. When the voltage of SS pin exceeds
the threshold voltage, the regulator starts operation. As the threshold is 0.62V(typ), the start delay time can be
calculated as follows:
ex. For setting at 1µF
C × V 1µ × 0.62
Td =
=
= 28.2 msec
i
22µ
3. Soft start function
1.5V
The internal PWM waveform has the voltage value as shown in the right.
If down-conversion from the voltage of V = 15V to 3.3V output to be made,
IN
for example, the PWM-ON duty has the value as shown below.
0.62V
PWM wave
V
OUT
+ VF
PWMduty =
= 25%
V
IN
- Vsat + VF
(Note that calculation is made with Vsat = 1V and VF = 0.2V)
The output voltage of error amplifier, which is 3.3V, is the value with PWM = 25%, as calculated in the above
equation, so that this voltage is determined as follows:
Ver = (∆VPWM) × PWMduty + VPWML = 0.88V × 0.25 + 0.62V = 0.84V
(∆VPWM is the PWM amplitude value or 0.88V(typ) while VPWML is the lower limit voltage of PWM
waveform or 0.62V(typ))
SS pin and error amplifier output voltages are designed to prefer the lower voltages, so that V
OUT
will reach the
designed regulation voltage in timing when the SS pin voltage exceeds the error amplifier output. Therefore, the soft
strt time is calculated as follows:
C × ∆VPWM × PWMduty C × 0.88 × PWMduty
Tss =
=
i
22µA
For the set conditions of C = 1µF and PWMduty = 25%:
1µ × 0.88V × 0.25
Tss =
= 10msec
22µA
No.A0951-4/5
LA5757TP
Timing Chart
V
IN
SW
OUT
OUT
V
Tss
Td
Overcurrent protection characteristic
Efficiency -- V
IN
90
85
80
75
70
65
60
8
V
V
C
=12V
=5V
IN
O
IN
7
6
5
4
3
2
1
0
=1000µF
C
=470µF
OUT
L=68µH
1.0A
0
10
20
30
40
0
0.4
0.8
1.2
1.6
2.0
Load current, I -- A
L
Input voltage, V -- V
I
-- VIN
IN
V sat -- I
STB
O
SW
250
200
150
100
50
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
0
10
20
30
40
0
0.25
0.5
0.75
1.0
1.25
1.5
Switch current, I
SW
-- A
Input voltage, V -- V
IN
No.A0951-5/5
LA5757TP
L
-- I
IN -- V
R IN
R
L
1.0
0.5
0
2.5
2.0
1.5
1.0
0.5
0
-0.5
-1.0
-0.5
0
5
10
15
20
25
30
0
0.25
0.5
0.75
1.0
1.25
1.5
Load current, I -- A
Input voltage, V -- V
IN
L
SANYO Semiconductor Co.,Ltd. assumes no responsibility for equipment failures that result from using
products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition
ranges, or other parameters) listed in products specifications of any and all SANYO Semiconductor Co.,Ltd.
products described or contained herein.
SANYO Semiconductor Co.,Ltd. strives to supply high-quality high-reliability products, however, any and all
semiconductor products fail or malfunction with some probability. It is possible that these probabilistic failures or
malfunction could give rise to accidents or events that could endanger human lives, trouble that could give rise
to smoke or fire, or accidents that could cause damage to other property. When designing equipment, adopt
safety measures so that these kinds of accidents or events cannot occur. Such measures include but are not
limited to protective circuits and error prevention circuits for safe design, redundant design, and structural
design.
In the event that any or all SANYO Semiconductor Co.,Ltd. products described or contained herein are
controlled under any of applicable local export control laws and regulations, such products may require the
export license from the authorities concerned in accordance with the above law.
No part of this publication may be reproduced or transmitted in any form or by any means, electronic or
mechanical, including photocopying and recording, or any information storage or retrieval system, or otherwise,
without the prior written consent of SANYO Semiconductor Co.,Ltd.
Any and all information described or contained herein are subject to change without notice due to
product/technology improvement, etc. When designing equipment, refer to the "Delivery Specification" for the
SANYO Semiconductor Co.,Ltd. product that you intend to use.
Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed
for volume production.
Upon using the technical information or products described herein, neither warranty nor license shall be granted
with regard to intellectual property rights or any other rights of SANYO Semiconductor Co.,Ltd. or any third
party. SANYO Semiconductor Co.,Ltd. shall not be liable for any claim or suits with regard to a third party's
intellctual property rights which has resulted from the use of the technical information and products mentioned
above.
This catalog provides information as of April, 2009. Specifications and information herein are subject
to change without notice.
PS No.A1439-6/6
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