EM8632J [EXCELLIANCE]
Green mode PWM Flyback Controller;
| 型号： | EM8632J |
| 厂家： | 
Excelliance MOS |
| 描述： | Green mode PWM Flyback Controller |
| 文件： | 总11页 (文件大小：285K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
EM8632
Green mode PWM Flyback Controller
General Description
Features
EM8632 is a high performance, low startup
current, low cost, current mode PWM controller
with green mode power saving. The EM8632
integrates functions of Soft Start(SS), Under Voltage
Lockout(UVLO), Leading Edge Blanking(LEB),
internal Over Temperature Protection(OTP),
internal slope compensation. The EM8632 also
features more protection like Over Load
Protection(OLP) and Over Voltage Protection(OVP)
to prevent circuit damage occurred under
abnormal conditions.
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Ultra Low Start Up Current (6uA)
Current Mode Control
Soft Start Function
Built-in Slope Compensation
Internal Leading-edge Blanking
UVLO
Over Voltage Protection (OVP) on VDD pin
Over Load Protection (OLP)
Cycle-by-cycle Current Limit
Feedback Open Protection
Internal Over Temperature Protection (OTP)
The EM8632 provides the users a superior
AC/DC power application of high efficiency,
excellent EMI performance, low external
component counts and lower cost solution.
Constant Output Power Limit (Full AC Input
Range)
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Excellent EMI performance
Ordering Information
Applications
Part Number
EM8632J
Package
Remark
ꢀ
ꢀ
Switching AC/DC Adaptor and charger
Open-Frame SMPS
SOT-23-6
EM8632S
DIP-8
Typical Application Circuit
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EM8632
Pin Configuration
Pin Assignment
Pin Number
Pin Name
Pin Function
SOT236
1
DIP8
8
Ground.
GND
Voltage feedback pin. By connecting a photo-coupler to close the control loop and
achieve the regulation.
COMP
2
7
Set the switching frequency by connecting a resistor to GND.
Senses the primary current.
RT
CS
3
4
5
6
--
5
4
2
IC Power Supply Pin.
VDD
GATE
NC
Gate drive output to drive the external MOSFET.
No Internal Connection.
1
3 & 6
Function Block Diagram
VDD
OVP
OTP
28V
Shutdown
Logic
OLP
15V / 9.8V
UVLO
Vbias
Green
mode
RT
COMP
CS
Oscillator
Max duty
2R
R
GATE
S
Q
Soft
Driver
LEB
-
R
Slope
Comp
+
PWM
comparator
-
Soft start
OCP
+
OCP
comparator
+
GꢀD
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EM8632
Absolute Maximum Ratings
ꢀ Supply Input Voltage, VDD ----------------------------------------------------------------------- 30V
(Note1)
ꢀ Gate pin------------------------------------------------------------------------------------------------ 30V
ꢀ RT, COMP, CS Pin ----------------------------------------------------------------------------------- - 0.3V to 6.5V
ꢀ Power Dissipation, PD @ TA = 25℃
SOT-23-6 ---------------------------------------------------------------------------------------------- 0.4W
DIP-8 ---------------------------------------------------------------------------------------------------- 0.714W
ꢀ Package Thermal Resistance
SOT-23-6 --------------------------------------------------------------------------------------------- 250℃/W
DIP-8 --------------------------------------------------------------------------------------------------- 140℃/W
ꢀ Junction Temperature ----------------------------------------------------------------------------- 150℃
ꢀ Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------- 260℃
ꢀ Storage Temperature Range ------------------------------------------------------------------- - 65℃ to 150℃
ꢀ ESD Susceptibility
(Note2)
HBM (Human Body Mode) ------------------------------------------------------------------------ 3KV
MM (Machine Mode) -------------------------------------------------------------------------------- 300V
ꢀ Gate Output Current---------------------------------------------------------------------------------- 300mA
Recommended Operating Conditions
(Note3)
ꢀ Supply Input Voltage, VDD ----------------------------------------------------------------------- 11V to 26V
ꢀ Operating Frequency ------------------------------------------------------------------------------ 50k to 130kHz
ꢀ Junction Temperature Range--------------------------------------------------------------------- -40℃ to 125℃
ꢀ Ambient Temperature Range-------------------------------------------------------------------- -40℃ to 85℃
Electrical Characteristics
(VDD=15V, RRT=100K ohm, TA=25℃, unless otherwise specified)
Parameter
VDD Section
Symbol
Test Conditions
Min
Typ
Max
Units
VDD OVP Protect voltage
Start up current
VOVP
26.5
28
29.6
V
ISTART1
ISTART2
VDD=7V
VDD= VTH-ON-0.5V
-
-
1
6
2
uA
uA
15
VDD On Threshold Voltage
VTH-ON
VTH-OFF
13.5
15
16.5
V
VDD Off Threshold Voltage
Operating Supply Current 1
Operating Supply Current 2
8.8
9.8
2
10.8
V
IDD-OP1 VDD=15V, VCOMP=0V,
-
-
3
-
mA
mA
VDD=15V, VCOMP=3V,
CGATE=1nF
IDD-OP2
2.5
VDD=15V,
IDD-OP3
Operating Supply Current 3
-
0.4
-
mA
Protection triggerred
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EM8632
Gate Section
Rising Time
TR
TF
CL = 1nF
CL = 1nF
-
-
150
30
200
100
nS
nS
Falling Time
Current-Sense Section
Maximum Internal Current
Setpoint
VCSLim
TLEB
TPD
0.8
0.85
300
100
2
0.9
V
Leading Edge Blanking Time
Propagation Delay Time
200
400
nS
nS
mS
Soft-Start Period
TSS
Internal Oscillator
Oscillation Frequency
fOSC
RRT=100K ohm
60
65
75
22
70
KHz
%
Maximum Duty
Dmax
VCOMP=3V, VCS=0V
Green mode minimum frequency
Frequency variation vs. VDD
KHz
%
VDD=11V to 25V
3
3
Frequency variation vs.
Temperature
-20℃ to 105℃(Note4)
%
COMP Section
COMP short to GND current
ICOMP
VCOMP
VGreen
VCOMP=0V
0.25
5.2
1
mA
V
Open loop COMP voltage
COMP pin open
Green mode COMP Threshold
Voltage
2.2
V
Protection Section
Open loop protection delay time Tdelay
56
4.8
160
mS
V
Open loop protection COMP Trip
voltage
VOLP
Internal Temperature Shutdown TSD
℃
Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for
stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended
periods may remain possibility to affect device reliability.
Note 2. Devices are ESD sensitive. Handling precaution is recommended.
Note 3. The device is not guaranteed to function outside its operating conditions.
Note 4. Guaranteed by design.
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EM8632
Typical Operating Characteristics
Temperature(℃)
Temperature(℃)
Fig1. UVLO (on) vs. Temperature
Fig2. UVLO (off) vs. Temperature
Temperature(℃)
Temperature(℃)
Fig3. Frequency vs. Temperature.
Fig4. Green Mode Frequency vs. Temperature.
Temperature(℃)
Temperature(℃)
Fig5. VCSLIM vs. Temperature.
Fig6. Start Up Current vs. Temperature.
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EM8632
Temperature(℃)
Fig7. OVP vs. Temperature.
Temperature(℃)
Fig8. VOLP-Trip vs. Temperature.
VDD (V)
Temperature(℃)
Fig10. Start Up Current vs. VDD
Fig9. Comp Open Voltage vs. Temperature.
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EM8632
Functional Description
UVLO
An UVLO comparator is implemented in EM8632 to
monitor the VDD pin voltage. As shown in Fig. 11, a
hysteresis is built in to prevent the shutdown from
the voltage drop during startup. The UVLO (on) and
UVLO (off) are setting at 15V and 9.8V,
respectively.
Fig. 12
Switching Frequency
To guarantee accurate frequency, EM8632 is
trimmed to 5% tolerance. The internal oscillator
also generates slope compensation, 75% maximum
duty limit. Connect a resistor form RT pin to GND
according to equation below to program the
switching frequency:
Fig. 11
Startup Operation
Fig. 12 shows a typical startup circuit and
transformer auxiliary winding for the EM8632
application, it consumes only startup current
(typical 6uA) and the current supplied through the
startup resistor charges the VDD capacitor (CVDD).
When VDD reaches UVLO (on) voltage, EM8632
begins switching and the current consumed
increases to 2mA. Then, the power required is
supplied from the transformer auxiliary winding.
The hysteresis of UVLO (off) provides more holdup
time, which allows using a small capacitor for VDD.
The ultra low startup current (typical 6uA) allow
system using higher resistance value of RStart. It
provides a fast startup and low power dissipation
solution.
fsw (KHz)= 6500/RT(KΩ)
Leading Edge Blanking (LEB)
Each time the power MOSFET turn on, the MOSFET
COSS, secondary rectifier reverse recovery current
and gate driver sourcing current comprise the
current spike. To avoid premature termination of
the switching pulse, a leading edge blanking time is
built in. During the blanking time (300nS), the
PWM comparator is off and cannot switch off the
gate driver. It is recommended to adopt a smaller
R-C filter (as show ad Fig.13) for high power
application to avoid the total spike width over
300nS leading edge blanking time.
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EM8632
within a fixed period of time. Reducing switching
events leads reduction on the power loss and
conserves the energy.
The EM8632 adjusts the switching mode according
to the load condition, the COMP pin voltage drops
below burst mode threshold level. Device enters
Burst Mode Control. The Gate drive output remains
at off state to minimize the switching loss and
reduces the standby power consumption.
Protection
The EM8632 provides many protection functions
that intend to protect system from being damaged.
All the protection functions are listed as below:
Fig. 13
ꢀ Cycle-by-cycle current limit
The EM8632 has over-current protection
thresholds (0.85V). It is for cycle-by-cycle
current limit, which turns off MOSFET for the
remainder of the switching cycle when the
sensing voltage of MOSFET current reaches the
threshold.
Soft Start
The EM8632 has an internal soft-start circuit that
increases cycle-by-cycle current limit comparator
inverting input voltage slowly after it starts. The
typical soft-start time is 2mS. The pulse width to
the power MOSFET is progressively increased to
establish the correct working conditions for
transformers, rectifier diodes and capacitors. The
voltage on the output capacitors is progressively
increased with the intention of smoothly
establishing the required output voltage. It also
helps prevent transformer saturation and reduces
the stress on the secondary diode during startup.
ꢀ Over-load / Open-loop Protection (OLP)
When feedback loop is open, as shown in Fig. 14,
no current flows through the opto-coupler
transistor, the EM8632 pulls up the COMP pin
voltage to 5.2V.
When the COMP pin voltage is above 4.8V
longer than 56mS, OLP is triggered. This
protection is also triggered when the SMPS
output drops below the normal value longer
than 56mS due to the overload condition.
Slope compensation
In the conventional application, the problem of the
stability is a critical issue for current mode
controlling, when it operates in high than 50% of
the duty cycle. The EM8632 built in saw-tooth
slope compensation. So it requires no extra
component.
Burst Mode Operation
At no load or light load condition, majority of the
power dissipation in switching power supply is
form switching loss on the power MOSFET, the
core loss of the transformer and the loss on the
snubber. The magnitude of power loss is in
proportion to the number of switching events
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EM8632
The system will hiccup, if the internal
temperature always high than 160℃.
ꢀ Pin open / short Protection
There are several open / short protections were
integrated in the EM8632 to prevent the power
supply or adapter from being damage. Under
the conditions list below, the gate output will
turn off to protect the system.
․RT pin short to GND
Fig. 14
ꢀ Over Voltage Protection (OVP) on VDD
The VGS ratings of the HV power MOSFETs are
often limited up to max 30V. To prevent the VGS
from the fault condition, the EM8632 are
implemented a Over-Voltage-Protection (OVP)
on VDD. Whenever the VDD voltage is high than
the OVP threshold voltage (28V), the output
gate drive will be shutdown to shop the
switching of the power MOSFET until the next
UVLO (on).
․RT pin open
․CS pin open
․COMP pin short to GND
The Over-Voltage-Protection on VDD function in
EM8632 is an auto-restart type protection. If the
OVP condition is not released, the VDD will
tripped the OVP level again and re-shutdown
the gate output. The VDD is working as a hiccup
mode as shown in Fig. 15. On the other hand, if
the OVP condition is removed, the VDD level will
go back to normal level and the output will
automatically return to the normal operation.
Fig. 15
ꢀ Internal Over-Temperature Protection (OTP)
Internal 160℃ comparator will provide over
temperature protection (OTP). OTP will
shutdown system, until VDD below UVLO(low).
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EM8632
Ordering & Marking Information
Device Name: EM8632J for SOT-23-6
F2: Device Code, F2 for EM8632J
ABC: Date Code
F2ABC
#1
Device Name: EM8632S for DIP-8
EM
8632
Device : EM8632S
ABCDEFG: Date Code
ABCDEFG
Outline Drawing
B
B1
e
G
D
A
F
b
A1
Dimension in mm
Dimension
A
A1
B
B1
b
C
D
e
F
G
Min.
0.90 0.00
1.15
0.30 0.08
0.30
0.45
Typ.
2.80 1.60
2.90 0.95
Max.
1.30 0.15
0.50 0.22
1.45 0.60
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EM8632
DIP-8
E1
EA
B1
e
B
D
Dimension in mm
A
Dimension
A1
A2
B
B1
C
D
E
E1
EA
e
L
Min.
0.381 3.17
9.01
6.22
7.36
8.5
2.92
Typ.
1.524 0.457 0.254
2.54
Max.
5.334
3.429
10.16 6.53
7.87
9.53
3.81
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