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PDF RT7736 Data sheet ( Hoja de datos )
| Número de pieza | RT7736 | |
| Descripción | PWM Flyback Controller | |
| Fabricantes | Richtek | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de RT7736 (archivo pdf) en la parte inferior de esta página. Total 23 Páginas | ||
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®
RT7736
SmartJitterTM PWM Flyback Controller
General Description
The RT7736 series is a high performance enhanced PWM
flyback controller with proprietary SmartJitterTM technology.
The innovative SmartJitterTM technology not only reduces
EMI emissions of SMPS when the system enters burst
switching green mode, but also eliminates output jittering
ripple.
The RT7736 is a current mode PWM controller including
built-in slope compensation, internal Leading Edge
Blanking (LEB) and cycle-by-cycle current limit. It provides
excellent green power performance, especially under light
load and no load conditions. It allows for simpler design
and reduces external component count.
This controller integrates comprehensive safety protection
functions for robust designs including input Under-Voltage
Lockout (UVLO), Over-Voltage Protection (OVP), Over-
Load Protection (OLP), Secondary Rectifier Short
Protection (SRSP), CS pin open protection and cycle-by-
cycle current limit.
The RT7736 is a cost-effective and compact solution for
NB adaptor applications. It is available in the SOT-23-6
package.
Features
Proprietary SmartJitterTM Technology
Reducing EMI Emissions of SMPS
Output Jittering Ripple Elimination
No Load Input Power Under 100mW (RT7736G/R/L/E)
Accurate Over Load Protection
UVLO 9V/14.5V
PRO Pin for External Arbitrary OVP/OTP
IC ON/OFF Control (RT7736G/R/L)
BNO Pin for Brown-In/Out (RT7736B/D/F)
Soft Driving for EMI Noise Reduction
Driver Capability : 300mA/−300mA
High Noise Immunity
RoHS Compliant and Halogen Free
Applications
Switching AC/DC Adaptor
DVD Open Frame Power Supply
Set-Top Box (STB)
ATX Standby Power
TV/Monitor Standby Power
PC Peripherals
NB Adaptor
Simplified Application Circuit
AC Mains
(90V to 265V)
Vo+
Vo-
PRO VDD GATE
COMP RT7736
GND
CS
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS7736-04 September 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1
1 page  
RT7736
VDD
BNO
COMP
CS
VBIN_TH/VBNO_TH
+
-
OVP
+
-
27V
Secondary Rectifier
Short Protection
2V -
Shutdown
Logic
OTP
POR
+ UVLO +
COMP Open
Sensing
Counter
- 9V/14.5V
Bias &
Bandgap
OLP
TOLP : 56ms (RT7736B)
TOLP : 88ms (RT7736D)
TOLP : 64ms (RT7736F)
Oscillator
5.2V
Constant
Power
Dmax
Soft Driver
S
Slope
Ramp
-
-
+
PWM
Comparator
Q
R
COMP
LEB X3
Burst Switching Green
Mode
VBURL
VBURH
VDD
GATE
GND
Figure 2. Block Diagram for RT7736B, RT7736D and RT7736F
Operation
Burst Switching Green Mode
The burst mode is designed to reduce switching loss.
When the output load reduces, and the VCOMP drops and
reaches VBURL, the controller will cease switching. After
output voltage decreases and the VCOMP goes up to VBURH,
the switching will be resumed.
VDD Holdup Mode
Under very light load conditions, the VDD may drop down
to turn-off threshold voltage. To avoid this situation when
VDD drops to a set threshold, VDD_ET, the hysteresis
comparator will bypass PWM and burst mode loop, and
then force switching at a very low level to supply energy
to VDD pin. VDD holdup mode is also improved to hold up
VDD by less switching cycles. This mode is very useful
for reducing start-up resistor loss and keeping start-up
time within specification. This function makes bias winding
design and transient design easier.
Oscillator
The oscillator runs at 65kHz and features frequency
jittering function. Its jittering depth is Δf with about TJIT
envelope frequency at fOSC. It also generates slope
compensation saw-tooth, maximum duty cycle pulse and
overload protection slope.
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS7736-04 September 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
5
5 Page 
Typical Operating Characteristics
IDD_ST vs. VDD
6
5
4
3
2
1
0
0 3 6 9 12 15
VDD (V)
VTH_ON vs. Temperature
16.0
15.5
15.0
14.5
14.0
13.5
13.0
-50
-25
0 25 50 75
Temperature (°C)
100 125
VDD_LH & VLH_OFF vs. Temperature
5.8
5.6
5.4 VDD_LH
5.2
5.0 VLH_OFF
4.8
-50
-25
0 25 50 75
Temperature (°C)
100 125
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS7736-04 September 2014
RT7736
IDD_ST vs. Temperature
10
8
6
4
2
-50
-25
0 25 50 75
Temperature (°C)
100 125
VTH_OFF vs. Temperature
10.0
9.5
9.0
8.5
8.0
-50
-25
0 25 50 75
Temperature (°C)
100 125
28.00
27.75
27.50
27.25
27.00
26.75
26.50
26.25
26.00
-50
VOVP vs. Temperature
-25 0
25 50 75 100 125
Temperature (°C)
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
11
11 Page | ||
| Páginas | Total 23 Páginas | |
| PDF Descargar | [ Datasheet RT7736.PDF ] | |
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