|
|
PDF LD7537 Data sheet ( Hoja de datos )
| Número de pieza | LD7537 | |
| Descripción | Green-Mode PWM Controller | |
| Fabricantes | Leadtrend | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LD7537 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
|
No Preview Available !
LD7537
12/15/2011
Green-Mode PWM Controller with Frequency Swapping
and Integrated Protections
Rev. 01a
General Description
The LD7537 is built-in with several functions, protection
and EMI-improved solution in a tiny package. It takes less
components counts or circuit space, especially ideal for
those total solutions of low cost.
The implemented functions include low startup current,
green-mode power-saving operation, leading-edge
blanking of the current sensing and internal slope
compensation. It also features more protections like
OLP (Over Load Protection) and OVP (Over Voltage
Protection) to prevent circuit damage occurred under
abnormal conditions.
Furthermore, the Frequency Swapping function is to
reduce the noise level and thus helps the power circuit
designers to easily deal with the EMI filter design by
spending minimum amount of component cost and
developing time.
Features
z High-Voltage CMOS Process with Excellent ESD
protection
z Very Low Startup Current (<20μA)
z Current Mode Control
z Green Mode Control
z UVLO (Under Voltage Lockout)
z LEB (Leading-Edge Blanking) on CS Pin
z Internal Frequency Swapping
z Internal Slope Compensation
z OVP (Over Voltage Protection) on Vcc Pin
z Brownout Protection
z OLP (Over Load Protection)
z 300mA Driving Capability
Applications
z Switching AC/DC Adaptor and Battery Charger
z Open Frame Switching Power Supply
Typical Application
AC
input
EMI
Filter
BNO
VCC
OUT
COMP
LD7537
GND
CS
DC
Output
photocoupler
Leadtrend Technology Corporation
LD7537-DS-01a December 2011
1
www.leadtrend.com.tw
Free Datasheet http://www.nDatasheet.com
1 page  
LD7537
Electrical Characteristics
(TA = +25°C unless otherwise stated, VCC=15.0V)
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Supply Voltage (Vcc Pin)
Startup Current
12 20 μA
Operating Current
(with 1nF load on OUT pin)
VCOMP=0V
VCOMP=3V
OLP Tripped/ Auto
1.0 mA
2.0 mA
0.47 mA
OVP Tripped /Latch
0.85 mA
Holding Current
Vcc=7V (latched)
430 μA
UVLO (off)
7.5 8.5 9.5
V
UVLO (on)
15 16 17
V
OVP Level
25 26 27
V
Voltage Feedback (Comp Pin)
Short Circuit Current
Open Loop Voltage
VCOMP=0V
COMP pin open
0.25 mA
5.4 V
Green Mode Threshold VCOMP
2.4 V
Zero Duty Threshold VCOMP
1.5 V
Zero Duty Hysteresis
100 mV
Current Sensing (CS Pin)
Maximum Input Voltage, VCS_OFF
Leading Edge Blanking Time
0.8 0.85 0.9
230
V
ns
Internal Slope Compensation
Input impedance
0% to DMAX. (Linearly increase)
300
1
mV
MΩ
Delay to Output
100 ns
Oscillator for Switching Frequency
Frequency, FREQ
60 65 70 kHz
Green Mode Frequency, FREQG
22 kHz
Trembling Frequency
± 4.0
kHz
Temp. Stability
(-20°C ~85°C)
5%
Voltage Stability
(VCC=11V-25V)
1%
Leadtrend Technology Corporation
LD7537-DS-01a December 2011
5
www.leadtrend.com.tw
Free Datasheet http://www.nDatasheet.com
5 Page 
LD7537
Internal Slope Compensation
In the conventional applications, the problem of the
stability is a critical issue for current mode controlling,
when it operates over 50% 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 LD7537 since it has
integrated it already.
On/Off Control
The LD7537 can be turned off by pulling COMP pin lower
than 1.5V. The gate output pin of the LD7537 will be
disabled immediately under such condition. The off-mode
can be released when the pull-low signal is removed.
Over Load Protection (OLP) - Auto
Recovery
To protect the circuit from damage due to over-load
condition and short or open-loop condition, the LD7537 is
implemented with smart OLP function. It also features
auto recovery function; see Fig. 18 for the waveform. In
case of fault condition, the feedback system will force the
voltage loop toward the saturation and then pull the
voltage high on COMP pin (VCOMP). When the VCOMP
ramps up to the OLP threshold of 4.5V and continues over
OLP delay time, the protection will be activated and then
turn off the gate output to stop the switching of power
circuit.
With the protection mechanism, the average input power
will be minimized to remain the component temperature
and stress within the safe operating area.
VCC
UVLO(on)
UVLO(off)
COMP
4.5V
OUT
OLP
UVLO(off)
OLP Reset
OLP delay time
OLP trip Level
t
t
Switching
Non-Switching
Switching
Fig. 18
t
OVP (Over Voltage Protection) on Vcc -
Latch mode
The Vcc OVP functions of LD7537 are latch mode.
Whenever the voltage on the Vcc pin is higher than the
OVP threshold, the output gate drive circuit will be
shutdown simultaneous to latch off the switching of the
power MOSFET. As soon as the voltage on Vcc pin drops
below OVP threshold and starts AC-recycling again, it will
recover to normal operation. Figure 19 shows its
operation.
Leadtrend Technology Corporation
LD7537-DS-01a December 2011
11
www.leadtrend.com.tw
Fig. 19
Free Datasheet http://www.nDatasheet.com
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LD7537.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 |