GR8837 [GRENERGY]
Green-Mode PWM Controller with Latch Protection;
| 型号： | GR8837 |
| 厂家： | 
Grenergy Opto, lnc. |
| 描述： | Green-Mode PWM Controller with Latch Protection |
| 文件： | 总14页 (文件大小：721K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Preliminary GR8837
Green-Mode PWM Controller with Latch Protection
Features
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Current mode control
Description
Standby power below 100mW
Under-voltage lockout (UVLO)
Non-audible-noise green-mode control
65KHz switching frequency
Internal leading-edge blanking
Internal slope compensation
Internal soft start
The GR8837 is a highly-integrated, low startup
current, current mode PWM controller with
green-mode function. This function enables the
power supply to easily meet even the strictest
power conservation requirements. The integrated
functions also include the leading-edge blanking
of the current sensing, internal slope com-
pensation, and soft start. OLP, OCP. The RTL pin
latch function by injecting a high over3.5V to
provide OVP latch off and low below 1V to provide
OTP latch off protection. To protect the external
power MOSFET from being damaged by supply
over voltage, the GR8837 OUT pin voltage is
clamped to about 13V.
Gate output voltage clamp
Jitter and soft driving for reducing EMI
External OVP Latch off mode
External OTP Latch off mode
Over-load protection (OLP)
300mA driving capability
The GR8837 improves the performance and
reduces the cost of power supplies. It is with 8-pin
DIP and 6-pin SOT-26 package.
Application
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Switching AC/DC Adapter
Battery Charger
Open frame SMPS
Ordering and Marking Information
SOT-26
7
DIP-8
Grenergy OPTO Inc. reserves the right to make changes to improve reliability or manufacture ability without notice, and
advise customers to obtain the latest version of relevant information to verify before placing orders.
2011.01 Ver. C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
1
Preliminary GR8837
Pin Configuration
GND
COMP
RTL
OUT
1
6
5
4
VCC
CS
2
3
Pin Description
Pin No.
Name
GND
Function
1
2
Ground pin
COMP
Voltage feedback pin, by connecting a photo-coupler to control the duty cycle
Resistor trigger latch off which a high over 3.5V for OVP latch off and a low below
1V for OTP latch
3
RTL
4
5
6
CS
Current sense pin, connect to sense the MOSFET current
Power supply pin
VCC
OUT
The output driver for driving the external MOSFET
Absolute Maximum Ratings
Supply voltage VCC --------------------------------------------------------------------------------------------------------- 30V
COMP, RTL, CS ---------------------------------------------------------------------------------------------------- -0.3 ~ 7V
OUT ----------------------------------------------------------------------------------------------------------- -0.3 ~ VCC + 0.3V
Junction temperature ------------------------------------------------------------------------------------------------------- 150
Operating ambient temperature ------------------------------------------------------------------------------ -20 ~ 85
Storage temperature range ---------------------------------------------------------------------------------- -65 ~ 150
SOT-26 package thermal resistance (junction to ambient) -------------------------------------------------- 250 /W
Power dissipation (SOT-26, at ambient temperature = 85
Power dissipation (DIP-8, at ambient temperature = 85
)
------------------------------------------------ 250mW
--------------------------------------------------- 650mW
)
Lead temperature (All Pb free packages, soldering, 10 sec) -------------------------------------------------- 260
ESD voltage protection, human body model -------------------------------------------------------------------------- 2KV
ESD voltage protection, machine model ------------------------------------------------------------------------------ 200V
2011.01 Ver. C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Preliminary GR8837
Electrical Characteristics (VCC = 15.0V & T
A
= +25
unless otherwise specified.)
Parameter
Pin
Min.
Typ.
Max.
Unit
SUPPLY VOLTAGE
Startup current (VCC=UVLO on - 1V)
5
5
5
8
800
2
15
uA
uA
Operating current (with 1nF load on OUT pin), Vcomp = 0V
Operating current (with 1nF load on OUT pin), Vcomp = 2.5V
Operating current (with 1nF load on OUT pin), protection tripped
(OLP, OVP)
1
3
1
mA
5
0.4
0.7
mA
UVLO(off)
5
5
5
5
5.8
10.3
27
6.8
11.3
28
7.8
12.3
29
V
V
UVLO(on)
OVP level on VCC pin
V
VCC level in Latch off mode (3Meg start-up resistor)
Holding current at latch off mode (VCC=5V)
Latch off mode release voltage
6
V
20
uA
V
5
3.2
VOLTAGE FEEDBACK
Short circuit current, Vcomp = 0V
2
2
2
2
0.8
5.5
mA
V
Open loop voltage, COMP pin open
Green-mode start voltage
4.4
1.5
V
Burst mode start voltage
0.85
V
CURRENT SENSING
Maximum input voltage, Vcs(off)
4
4
4
0.80
1
0.85
350
0.9
V
nS
M
Leading-edge blanking time
Input impedance
Delay to Output
4
100
nS
OSCILLATOR
Frequency
-
-
-
-
-
60
20
65
+6
22
70
KHz
%
Jitter frequency
Green mode frequency
25
5
KHz
%
Temp. stability 40°C ~ 110°C)
Voltage stability (VCC = 11V~25V)
3
%
GATE DRIVER OUTPUT
Output low level, VCC = 15V, Io = 20mA
6
6
6
6
6
1
V
V
Output high level, VCC = 15V, Io = 20mA
Rising time, load capacitance = 1000pF
Falling time, load capacitance = 1000pF
VGATE-clamp (VCC = 25V )
8
200
80
nS
nS
V
12
13
2011.01 Ver. C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Preliminary GR8837
OLP SECTION
OLP trip level, Vcomp (OLP)
-
3.5
60
V
OLP delay time
-
mS
PWM SECTION
Maximum duty cycle
-
70
75
80
%
RTL SECTION
Over Voltage Protection threshold voltage
3
3
3
3
3
3
3.2
3.5
100
1
3.8
V
uS
V
OVP Debounce time
Over Temperature Protection threshold voltage
OTP Debounce time
0.95
1.05
100
80
us
uA
V
Output current from RTL pin
RTL Pin voltage when floating
75
85
1.8
2.4
3.0
2011.01 Ver. C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Preliminary GR8837
Typical Performance Characteristics
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Preliminary GR8837
2011.01 Ver. C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Preliminary GR8837
Application Information
frequency of the controller will decrease so as to
reduce the system power consumption. The
minimum frequency is about 22 KHz, which is
Start-up Current
The typical start-up current is around 8uA. Very low
start-up current allows the PWM controller to
increase the value of start-up resistor and then
reduce the power dissipation on it.
outside the audio range
.
LEB (Leading-Edge Blanking)
Each time the power MOSFET is switched on, a
turn-on spike will inevitably occur at the sense
resistor. To avoid fault trigger, a 350ns leading-edge
blanking time is built in. Conventional RC filtering
can therefore be omitted. During this blanking
period, the current-limit comparator is disabled and
can not switch off the gate driver.
UVLO (Under Voltage Lockout)
A hysteresis UVLO comparator is implemented in
GR8837, then the turn-on and turn-off thresholds
level are fixed at 11.3V and 6.8V respectively. This
hysteresis shown in Fig.9 ensures that the start-up
capacitor will be adequate to supply the chip during
start-up. The GR8837 is designed to meet the
standby power below 100mW. So the start-up
resistor can be used as several Mega Ohms to
reduce the power loss. Due to the low UVLO on
level, so the turn-on delay time will also never
greater than the general PWM IC.
Internal Slope Compensation
A built-in slope compensation circuit is constructed
in GR8837. When the switch is on, a ramp voltage is
added to the sensed voltage across the CS pin,
which helps to stabilize the system and prevent the
sub-harmonic oscillations
.
OLP (Over Load Protection)
The GR8837 has over load protection function. An
internal circuit detects the load level, when the load
is larger than a threshold level and the condition
lasts more than 60ms, the gate output will keep on
low level. Then VCC decreases below UVLO off
level, the controller resets again. Fig.10 shows the
waveform of the OLP operation.
Fig.9
Soft Start
During initial power on, the GR8837 provides 16ms
soft start function. It effectively suppresses the start
up peak current to reduce the power MOSFET drain
voltage especially at high line.
Oscillator
The maximum duty-cycle of internal oscillator is
limited to 75% for avoiding the transformer
saturation. The frequency of the oscillator is fixed to
65KHz by internal setting.
Green-Mode Operation
Fig. 10
When the load decreases to an extent, the
2011.01 Ver. C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
7
Preliminary GR8837
OVP (Over Voltage Protection) on VCC
voltage will down to UVLO off and the IC will re-start
again. In the GR8837, before the VCC is down to
UVLO off, it will force the OUT pin outputs the
specified duty to pull the VCC higher than UVLO off.
The operation is shown in Fig.12.
To prevent power MOSFET from being damaged,
the GR8837 is implemented an OVP function on
VCC. When the VCC voltage is higher than the OVP
threshold voltage, the output gate driver circuit will
be shut down immediately to stop the switching of
power MOSFET. The VCC pin OVP function is a
latch off type protection. If the OVP condition
happens, the pulses will be stopped and never
recovery unless the VCC pin voltage is down to
reset level. The GR8837 is working in a latch off
mode as shown in Fig. 11.
VCC
VCC mode
Burst mode
VCC mode(off)
VCC mode(on)
UVLO(off)
t
t
t
LOAD
Full load
OUT
Switching
Fig. 12
The VCC mode function is used to prevent the
output re-start again when load changes. So never
let the system operate on the VCC mode at no load.
The system should operate on burst mode,
Fig. 11
Gate Clamp/Soft Driving
Driver is clamped to 13V by an internal clamping
circuit. Those damages usually come from
undesired over-voltage gate signals. Under the
conditions listed below, the gate output will turn off
immediately to protect the power circuit. The
GR8837 also has soft driving function to minimize
EMI.
otherwise the input power maybe become larger.
RTL Pin Latch Off Mode
VCC Mode Operation
In order to avoid the output voltage shut down by
load changing from full to no load, the GR8837 is
built-in the VCC mode function. When the load from
full changes to no load, the output voltage will
overshoot and pull low the COMP pin by feedback
loop. Thus the duty will disappear and no power
delivers to the secondary. If there is without any
Fig. 13
The typical application for RTL pin is shown in Fig.
13. The Zener diode is setting as external OVP
mechanism to prevent this situation, the VCC pin
2011.01 Ver. C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Preliminary GR8837
protection and the NTC thermistor is setting as
external OTP protection. In the RTL pin, there are
two comparators for latch-off mode protection. While
the voltage on this pin is higher than 3.5V or lower
than 1.0V, the GR8837 will shut down after the
de-bounce time 100us. And the GR8837 will never
auto recovery, unless the VCC pin voltage is down
to reset level as same as shown in Fig. 11.
2011.01 Ver. C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
9
Preliminary GR8837
Typical Application Circuit
1
5
GND
VCC
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Preliminary GR8837
Package Information
SOT-26
SOT-26
SYMBOL
MILLIMETERS
INCHES
MIN.
MAX.
1.45
0.15
1.30
0.50
0.22
3.10
3.00
1.80
MIN.
MAX.
0.057
0.006
0.051
0.020
0.009
0.122
0.118
0.071
A
A1
A2
b
0.00
0.90
0.30
0.08
2.70
2.60
1.40
0.000
0.035
0.012
0.003
0.106
0.102
0.055
c
D
E
E1
e
0.95 BSC
1.90 BSC
0.037 BSC
0.075 BSC
e1
L
0.30
0o
0.60
8 o
0.012
0o
0.024
8 o
Note: 1. Followed from JEDEC TO-178 AB.
2. Dimension D and E1 do not include mold flash, protrusions or gate burrs. Mold flash, protrusions or
gate burrs shall not exceed 10 mil per side
2011.01 Ver. C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Preliminary GR8837
Package Information
DIP-8
DIP-8
SYMBOL
MILLIMETERS
INCHES
MIN.
MAX.
5.33
MIN.
MAX.
0.210
A
A1
A2
b
0.38
2.92
0.36
1.14
0.20
9.01
0.13
7.62
6.10
0.015
0.115
0.014
0.045
0.008
0.355
0.005
0.300
0.240
4.95
0.56
1.78
0.35
10.16
0.195
0.022
0.070
0.014
0.400
b2
c
D
D1
E
8.26
7.11
0.325
0.280
E1
e
2.54 BSC
7.62 BSC
0.100 BSC
0.300 BSC
eA
eB
L
10.92
3.81
0.430
0.150
2.92
0.115
Note: 1. Followed from JEDEC MS-001 BA.
2. Dimension D, D1 and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not
exceed 10 mil.
2011.01 Ver. C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Preliminary GR8837
Carrier Tape & Reel Dimensions
SOT-26
Application
A
H
T1
C
d
D
W
E1
F
8.4+2.00 13.0+0.50
178.0 2.00 50 MIN.
1.5 MIN. 20.2 MIN. 8.0 0.30 1.75 0.10 3.5 0.05
-0.00
-0.20
D0
SOT-26
P0
P1
P2
D1
T
A0
B0
K0
0.6+0.00
-0.40
1.5+0.10
-0.00
4.0 0.10
4.0 0.10 2.0 0.05
1.0 MIN.
3.20 0.20 3.10 0.20 1.50 0.20
Application
SOT -26
Carrier Width
Cover Tape Width
Devices Per Reel
8
5.3
3000
(mm)
2011.01 Ver. C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Preliminary GR8837
Tape and Specification Reel
SOT 26
Direction of feed
______________________________________________________________________
Grenergy OPTO, Inc. reserves the right to make corrections, modifications, enhancements, improvements, and other changes
to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the
latest relevant information before placing orders and should verify that such information is current and complete.
2011.01 Ver. C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
14
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