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PDF LD5761 Data sheet ( Hoja de datos )
| Número de pieza | LD5761 | |
| Descripción | High Voltage with Two-Level Frequency Green-Mode PWM Controller | |
| Fabricantes | Leadtrend Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LD5761 (archivo pdf) en la parte inferior de esta página. Total 19 Páginas | ||
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High Voltage with Two-Level Frequency
Green-Mode PWM Controller
LD5761
05/28/2015
REV: 01
General Description
The LD5761 is a Green Mode PWM IC which is built-in with
brown-in/out functions in a SOP-7/SOP-8 package. The
device could minimize the component counts, circuit space,
and reduces the overall material cost of power applications.
The two-level frequency of operation enables excellent
performance and high efficiency at nominal line. While in
low line, just operate in high-level frequency to reduce BMAX.
Without changing transformer design, the energy loss is
perfectly minimized.
With complete protections in it, like OLP (Over Load
Protection), OVP (Over Voltage Protection), fast OSCP
(Output short circuit protection) and brown-in/out protection,
the LD5761 protects the circuit from being damaged in
abnormal conditions.
Furthermore, the LD5761 features frequency swapping and
soft driving function to minimize the noise and enhance EMI.
Typical Application
AC
Input
EMI
Filter
~+
~
Features
High-Voltage (650V) Start-up Circuit
No-Load Power Consumption <30mW @230Vac
with X-cap discharge
Two-Level Frequency Operation at H/L Line
Built- in Brown-in/out Function on HV pin
Built- in X-Cap Discharge on HV pin
Frequency Swapping for EMI Enhancement
Non-Audible-Noise Green Mode Control
LEB (Leading-Edge Blanking) on CS Pin
Internal Slope Compensation
OVP (Over Voltage Protection) on VCC
OLP (Over Load Protection)
OTP (Over Temperature Protection)
OSCP(Output Short Circuit Protection)
Soft Driving
+300mA/-800mA Driving Capability
Applications
Switching AC/DC Adaptor and Battery Charger
Open Frame Switching Power Supply
LCD Monitor/TV Power
DC
Output
HV VCC OUT
OTP
GND
LD5761
COMP CS
*
Leadtrend Technology Corporation
LD5761-DS-01 May 2015
1
www.leadtrend.com.tw
1 page  
Electrical Characteristics
(TA = +25oC unless otherwise stated, VCC=15V)
PARAMETER
CONDITIONS
High-Voltage Supply (HV Pin)
HV Pin Source Current
VCC <UVLO(ON),
HV=500V
HV Pin Discharge Capability HV=500V
HV Pin Leakage Current
VCC >UVLO(ON),
HV=500V
HV Pin Brown-In Level
HV Pin Brown-Out Level
HV Pin Hysteresis
Brown-In De-bounce Time
VHVBI - VHVBO
Brown-Out De-bounce Time
Low Frequency Operation
Range
High Frequency Operation
Range
HV Pin Min. Operation
Voltage
Vcc =15V
X-Cap discharge Detection
VCOMP =3V
Delay time
Supply Voltage (VCC Pin)
Start-up Current
HV=500V
Operating Current
(with 1nF load on OUT pin)
VCOMP=3V
VCOMP=0V
OTP Latch mode
Latch mode
UVLO(OFF)
UVLO(ON)
PDR
VCC HVBI Level
VCC > VHVBI, see Fig.1
SYMBOL
IHV
IHV_DIS
IHV_LEAK
VHVBI
VHVBO
VHVB_HYS
TD_HVBI
TD_HVBO
VLSW
VHSW
VHV_MIN
TD_XCAP
ICC_ST
ICC_OP1
ICC_OP2
ICC_OPLL
ICC_OPL
VCC_OFF
VCC_ON
VCC_PDR
VCC_HVBI
MIN TYP
2.6 2.9
2.2 2.6
94.5 105
82.8 92
13
160
67
265
45
65
0.38
6
15
25
2
0.42
0.55
0.65
7
16
UVLOOFF
- 1.4V
UVLOOFF
+4V
LD5761
05/28/2015
MAX UNITS
3.3
3.0
35
115.5
96.6
mA
mA
A
VDC
VDC
VDC
S
mS
VDC
195 VDC
V
mS
50 A
mA
0.46 mA
mA
mA
8V
17 V
V
V
Leadtrend Technology Corporation
LD5761-DS-01 May 2015
5
www.leadtrend.com.tw
5 Page 
Application Information
Operation Overview
As long as the green power requirement becomes a trend
and the power saving is getting more and more important
for the switching power supplies and switching adaptors,
the traditional PWM controllers are not able to support
such new requirements. Furthermore, the cost and size
limitation force the PWM controllers to be more powerful
and with more functions to reduce the external part counts.
The LD5761 is ideal for these applications. Its detailed
features are described as below.
Internal High-Voltage Start-up Circuit and
Under Voltage Lockout (UVLO)
The traditional circuit provides the start-up current through
a start-up resistor to power up the PWM controller.
However, it consumes much significant power to meet the
current power saving requirement. In most cases, start-up
resistors carry larger resistance and spend more time to
start-up.
To achieve the optimized topology, as shown in Fig. 11,
LD5761 is implemented with a high-voltage start-up circuit
for such requirement. At start-up, the high-voltage current
source sinks current of AC Line or Neutral to provide
start-up current and charge the capacitor C1 connected to
VCC.
At the start-up transient, the HV current will supply around
2.9mA to VCC capacitor until this VCC voltage reaches
the UVLO(on). By using such configuration, the turn-on
delay time will be almost same no matter under low-line or
high-line conditions.
AC
Input
EMI
Filte
r
LD5761
05/28/2015
~+
~
HV VCC OUT
OTP LD5761
GND
CS
Fig. 11
As VCC trips UVLO(off), HV pin will recharge VCC
capacitor till VCC voltage rises back to UVLO(on) again.
Since then, HV pin would no longer charge the capacitor
and instead, send a gate drive signal to draw supply
current for VCC from the auxiliary winding of the
transformer. That minimizes the power loss on the start-up
circuit successfully.
An UVLO comparator is embedded to detect the voltage
across the VCC pin to ensure the supply voltage enough
to power on the LD5761 and in addition, to drive the power
MOSFET. As shown in Fig. 12, a hysteresis is provided to
prevent shutdown from the voltage dip during start-up.
The turn-on and turn-off threshold level are set at 16V and
7V, respectively.
Leadtrend Technology Corporation
LD5761-DS-01 May 2015
11
www.leadtrend.com.tw
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet LD5761.PDF ] | |
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