|
|
PDF LD7535 Data sheet ( Hoja de datos )
| Número de pieza | LD7535 | |
| Descripción | Green-Mode PWM Controller | |
| Fabricantes | Leadtrend Technology | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LD7535 (archivo pdf) en la parte inferior de esta página. Total 19 Páginas | ||
|
No Preview Available !
LD7535/LD7535A
12/11/2007
Green-Mode PWM Controller with Integrated Protections
Rev. 01c
General Description
The LD7535/LD7535A are low cost, low startup current,
current mode PWM controllers with green-mode power-
saving operation. The integrated functions include the
leading-edge blanking of the current sensing, internal slope
compensation and the tiny package of SOT-26. They
provide the users a superior AC/DC power application of
higher efficiency, low external component counts, and lower
cost solution.
Furthermore, LD7535/LD7535A features more protections
like OLP (Over Load Protection) and OVP (Over Voltage
Protection) to eliminate the external protection circuits. And
to satisfy different designs, 2 versions of OVP levels are
implemented as ---
z LD7535 --- 28.0V ± 1.5V.
z LD7535A --- 21.0V ± 1.5V.
Features
z High-Voltage CMOS Process with Excellent ESD
protection
z Very Low Startup Current (<20μA)
z Current Mode Control
z Non-audible-noise Green Mode Control
z UVLO (Under Voltage Lockout)
z LEB (Leading-Edge Blanking) on CS Pin
z Programmable Switching Frequency
z Internal Slope Compensation
z OVP (Over Voltage Protection) on Vcc Pin
z OLP (Over Load Protection)
z 300mA Driving Capability
Applications
z Switching AC/DC Adaptor and Battery Charger
z Open Frame Switching Power Supply
z 384X Replacement
Typical Application
1
Lweawdtwren.Dd aTetcahSnhoeloegty4UCo.rnpeotration www.leadtrend.com.tw
LD7535&LD7535A-DS-01c December 2007
1 page  
Absolute Maximum Ratings
Supply Voltage VCC
COMP, RT, CS
Junction Temperature
Operating Ambient Temperature
Storage Temperature Range
Package Thermal Resistance (SOT-26)
Package Thermal Resistance (DIP-8)
Power Dissipation (SOT-26, at Ambient Temperature = 85°C)
Power Dissipation (DIP-8, at Ambient Temperature = 85°C)
Lead temperature (Soldering, 10sec)
ESD Voltage Protection, Human Body Model
ESD Voltage Protection, Machine Model
Gate Output Current
LD7535/LD7535A
30V
-0.3 ~7V
150°C
-40°C to 85°C
-65°C to 150°C
250°C/W
100°C/W
250mW
650mW
260°C
3KV
250V
300mA
Caution:
Stresses beyond the ratings specified in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only
rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not
implied.
Recommended Operating Conditions
Item
Supply Voltage Vcc (LD7535)
Supply Voltage Vcc (LD7535A)
Switching Frequency
Startup Resistor Value
Min.
11
11
50
1.2
Max.
25
18
130
4.4
Unit
V
V
KHz
MΩ
5
Leadtrend Technology Corporation www.leadtrend.com.tw
LD7535&LD7535A-DS-01c December 2007
5 Page 
LD7535/LD7535A
V−(PWMCOMPARATOR )
=
1
3
×
(
VCOMP
− 2VF )
A pull-high resistor is embedded internally and can be
eliminated externally.
Internal Slope Compensation
In the conventional application, the problem of the stability is
a critical issue for current mode controlling, when it operates
in higher than 50% of the duty-cycle. As UC384X, It takes
slope compensation from injecting the ramp signal of the
RT/CT pin through a coupling capacitor. It therefore requires
no extra design for the LD7535/LD7535A since it has
integrated it already.
The Vcc OVP function in LD7535/LD7535A is an
auto-recovery type protection. If the OVP condition,
usually caused by the feedback loop opened, is not
released, the Vcc will tripped the OVP level again and
re-shutdown the output. The Vcc is working as a hiccup
mode. The Figure. 18 shows its operation.
On the other hand, if the OVP condition is removed, the Vcc
level will get back to normal level and the output will
automatically return to the normal operation.
On/Off Control
The LD7535/LD7535A can be turned off by pulling COMP
pin lower than 1.2V. The gate output pin of the
LD7535/LD7535A will be disabled immediately under such
condition. The off-mode can be released when the pull-low
signal is removed.
Dual-Oscillator Green-Mode Operation
There are many different topologies has been implemented
in different chips for the green-mode or power saving
requirements such as “burst-mode control”, “skipping-cycle
mode”, “variable off-time control “…etc. The basic operation
theory of all these approaches intended to reduce the
switching cycles under light-load or no-load condition either
by skipping some switching pulses or reduce the switching
frequency.
By using this dual-oscillator control, the green-mode
frequency can be well controlled and further to avoid the
generation of audible noise.
OVP (Over Voltage Protection) on Vcc
The VGS ratings of the nowadays power MOSFETs are often
limited up to max. 30V. To prevent the VGS from the fault
condition, LD7535/LD7535A are implemented an OVP
function on Vcc. Whenever the Vcc voltage is higher than
the OVP threshold voltage, the output gate drive circuit will
be shutdown simultaneously thus to stop the switching of
the power MOSFET until the next UVLO(on).
Fig. 18
The OVP levels are ---
z LD7535 --- 28.0V ± 1.5V.
z LD7535A --- 21.0V ± 1.5V.
Over Load Protection (OLP)
To protect the circuit from being damaged under over load
condition or short condition, a smart OLP function is
implemented in the LD7535/LD7535A. The figure 20 shows
the waveforms of the OLP operation. In this case, the
feedback system will force the voltage loop proceed toward
the saturation and then pull up the voltage on COMP pin
(VCOMP). Whenever the VCOMP trips up to the OLP threshold
5V and stays longer than 60mS, the protection will activate
and then turn off the gate output to stop the switching of
power circuit. The 60mS delay time is to prevent the false
trigger from the power-on and turn-off transient.
By such protection mechanism, the average input power
can be reduced to very low level so that the component
temperature and stress can be controlled within the safe
operating area.
11
Leadtrend Technology Corporation www.leadtrend.com.tw
LD7535&LD7535A-DS-01c December 2007
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet LD7535.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LD7530 | Green-Mode PWM Controller | Leadtrend Technology |
| LD7530A | Green-Mode PWM Controller | Leadtrend Technology |
| LD7531 | Green-Mode PWM Controller | Leadtrend Technology |
| LD7531A | Green-Mode PWM Controller | Leadtrend Technology |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |