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Preliminary GR8837E
Green-Mode PWM Controller with Latch Protection
Features
Current Mode Control
Standby Power below 100mW
Non-Audible-Noise Green-Mode Control
65KHz Switching Frequency
Internal Leading-Edge Blanking
Internal Slope Compensation
Internal Soft Start
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)-Auto Recovery
Mode
Vcc OVP Protection- Latch Mode
Description
The GR8837E is a highly-integrated, low startup
current, current mode PWM controller with
green-mode function. The integrated functions also
include the leading-edge blanking of the current
sensing, internal slope compensation, soft start
OLP, and OCP. Besides, The RTL pin latch function
by injecting a high over 3.5V to provide OVP latch
off and low below 1V to provide OTP latch off
protection. These functions enable the power supply
to easily meet even the strictest power
requirements.
The GR8837E improves the performance and
reduces the cost of power supplies. It is a 6-pin
SOT-26 package which could drive up to around
400mA Driving Capability
Application
Switching AC/DC Adapter
Battery Charger
Open Frame SMPS
Ordering and Marking Information
SOT-26
65W power converter.
Code 1 8 9 A B
Year 2008 2009 2010 2011
Code 2 1 2 3 4 9 A B C
Month Jan. Feb. Mar. Apr.
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.
2012.04 Ver.C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
● ● ●
G H I J
2016 2017 2018 2019
Sep. Oct. Nov. Dec.
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Preliminary GR8837E
Pin Configuration
GND
1
6
OUT
COMP
2
5
VCC
RTL
3 4
CS
Pin Description
Pin No. Name Function
1 GND Ground pin
2 COMP Voltage feedback pin, by connecting a photo-coupler to control the duty cycle
3 RTL
4 CS Current sense pin, connect to sense the MOSFET current
Resistor trigger latch off which a high over 3.5V for OVP latch off and a low below
1V for OTP latch
5 VCC Power supply pin
6 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℃) ------------------------------------------------ 250mW
Lead temperature (All Pb free packages, soldering, 10 sec) -------------------------------------------------- 260℃
ESD voltage protection, human body model -------------------------------------------------------------------------- 2KV
ESD voltage protection, machine model ------------------------------------------------------------------------------ 200V
2012.04 Ver.C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Block Diagram
Preliminary GR8837E
2012.04 Ver.C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Preliminary GR8837E
Electrical Characteristics
Parameter Pin
SUPPLY VOLTAGE
Startup Current (VCC=UVLO on - 1V) 5 8 15 uA
Operating Current (with 1nF load on OUT pin), Vcomp = 0V 5 800 uA
Operating Current (with 1nF load on OUT pin), Vcomp = 2.5V 5 1 2 3 mA
Operating Current (with 1nF load on OUT pin), Protection
Tripped (OLP, OVP)
UVLO(off) 5 7.0 V
UVLO(on) 5 11.5 V
OVP Level on VCC Pin-Latch Mode 5 27 28 29 V
VCC Level in Latch Mode (3Meg start-up resistor) 5 6 V
Holding Current at Latch Mode (VCC=5V) 20 uA
Latch Mode Release Voltage 5 3.2 V
VOLTAGE FEEDBACK
Short Circuit Current, Vcomp = 0V 2 0.8 mA
(VCC = 15.0V & TA = +25℃,unless otherwise specified.)
Min. Typ. Max. Unit
5 0.4 0.7 1 mA
Open Loop Voltage, COMP Pin Open 2 4.4 5.5 V
Green-Mode Start Voltage 2 1.5 V
Burst Mode Start Voltage 2 0.85 V
CURRENT SENSING
Maximum Input Voltage, Vcs(off)-Auto Recovery Mode 4 0.80 0.85 0.9 V
Leading-Edge Blanking Time 4 350
Input Impedance 4 1
Delay to Output 4 100 nS
OSCILLATOR
Frequency - 60 65 70 KHz
Jitter Frequency - +6 %
Green Mode Frequency - 22 KHz
Temp. Stability (-40°C ~ 110°C)
Voltage Stability (VCC = 11V~25V) - 3 %
GATE DRIVER OUTPUT
Output Low Level, VCC = 15V, Io = 20mA 6 1 V
- 5 %
nS
MΩ
Output High Level, VCC = 15V, Io = 20mA 6
Rising Time, Load Capacitance = 1000pF 6 150 nS
Falling Time, Load Capacitance = 1000pF 6
VGATE-Clamp (VCC = 25V ) 6 12 13 V
2012.04 Ver.C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
8 V
80 nS
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OLP SECTION
OLP Trip Level, Vcomp (OLP) - 3.5 V
OLP Delay Time - 60 mS
PWM SECTION
Maximum Duty Cycle - 70 75 80 %
RTL SECTION
Over Voltage Protection Threshold Voltage 3 3.2 3.5 3.8 V
OVP Debounce Time 3 100 uS
Over Temperature Protection Threshold Voltage 3 0.95 1 1.05 V
OTP Debounce Time 3 100 us
Output Current from RTL Pin 3 75 80 85 uA
RTL Pin voltage When Floating 3 1.8 2.4 3.0 V
Preliminary GR8837E
2012.04 Ver.C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Typical Performance Characteristics
Preliminary GR8837E
2012.04 Ver.C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Preliminary GR8837E
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Preliminary GR8837E
Application Information
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.
UVLO (Under Voltage Lockout)
A hysteresis UVLO comparator is implemented in
GR8837E, then the turn-on and turn-off thresholds
level are fixed at 11.5V and 7.0V respectively. This
hysteresis shown in Fig.9 ensures that the start-up
capacitor will be adequate to supply the chip during
start-up. The GR8837E 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
reduce the system power consumption. The
minimum frequency is about 22 KHz, which is
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.
Internal Slope Compensation
A built-in slope compensation circuit is constructed
in GR8837E. When the switch is on, a ramp voltage
is added to the sensed voltage across the CS pin,
.
level, so the turn-on delay time will also never
greater than the general PWM IC.
Fig.9
Soft Start
During initial power on, the GR8837E 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
When the load decreases to an extent, the
frequency of the controller will decrease so as to
2012.04 Ver.C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
which helps to stabilize the system and prevent the
sub-harmonic oscillations
OLP (Over Load Protection)
The GR8837E 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. 10
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OVP (Over Voltage Protection) on VCC
To prevent power MOSFET from being damaged,
the GR8837E 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 type protection. GR8837E is working in latch
mode as shown in Fig. 11.
Preliminary GR8837E
Fig. 12
The VCC mode function is used to prevent the
output re-start again when load changes. So never
Fig. 11
Gate Clamp/Soft Driving
Driver is clamped to 13V by an internal clamping
circuit. A totem pole gate driver is fine tuned to meet
both EMI and efficiency requirement in low power
application. An internal pull low circuit is activated
after pretty low Vdd to prevent external MOSFET
from accidentally turning on during UVLO.
VCC Mode Operation
In order to avoid the output voltage shut down by
load changing from full to no load, the GR8837E 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
mechanism to prevent this situation, the VCC pin
voltage will down to UVLO off and the IC will re-start
again. In the GR8837E, 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.
let the system operate on the VCC mode at no load.
The system should operate on burst mode,
otherwise the input power maybe become larger.
RTL Pin Latch Off Mode
Fig. 13
The typical application for RTL pin is shown in Fig.
13. The Zener diode is setting as external OVP
protection and the NTC thermal resistor 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 GR8837E will shut down after the
de-bounce time 100us. And the GR8837E will never
auto recovery, unless the VCC pin voltage is down
to reset level as same as shown in Fig. 11.
2012.04 Ver.C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Typical Application Circuit
Preliminary GR8837E
T1B
10R / 1206
R17
NC
COMP
VCC
OUT
R9
500K / 1206
NC
C3
20V
DZ1
2
5
R6
BAV103
D4
10u/50V
C6
0.1uF
C5
PC817
U2B
10nF
C9
0R
R18
1K
GND
R16
3
RTL
GR8837
U1
CS
100K
NTC2
10nF
CT
1
N
Short
NTC1
500K / 1206
R5
68u/400V
C1
51K / 1206
R3
MOV1
NC
0.1uF
CX1
51K / 1206
R2
L
T2A/250V
F1
L1
GBU206
DB1
4
100pF
C4
100R
R7
1R / 1206
R14
1R / 1206
R15
431
U3
0.1uF
C10
27K
R27
6
10R
R8
10R / 1206
R1
PR1007
10K
R12
6N60C
Q1
100R
U2A
PC817
R22
107K
R23
D2
CY1
470u/25V
2200pF / 1206
75R / 1206
470u/25V
C2
R4
T1A
22R / 1206
20A100V
D1
C7
C8
L2
RS1
1000pF / 1206
CS1
-
12V/3.0A
+
2012.04 Ver.C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Package Information
SOT-26
Preliminary GR8837E
SYMBOL
A 1.45 0.057
A1 0.00 0.15 0.000 0.006
A2 0.90 1.30 0.035 0.051
b 0.30 0.50 0.012 0.020
c 0.08 0.22 0.003 0.009
D 2.70 3.10 0.106 0.122
E 2.60 3.00 0.102 0.118
E1 1.40 1.80 0.055 0.071
e 0.95 BSC 0.037 BSC
e1 1.90 BSC 0.075 BSC
L 0.30 0.60 0.012 0.024
θ 0o 8 o 0o 8 o
Note: 1. Followed from JEDEC TO-178 AB.
MILLIMETERS INCHES
MIN. MAX. MIN. MAX.
SOT-26
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
2012.04 Ver.C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
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Carrier Tape & Reel Dimensions
SOT-26
Preliminary GR8837E
Application
SOT-26
Application Carrier Width Cover Tape Width Devices Per Reel
SOT -26 8 5.3 3000
A H T1 C d D W E1 F
178.0±2.00 50 MIN.
P0 P1 P2 D0 D1 T A0 B0 K0
4.0±0.10 4.0±0.10 2.0±0.05
8.4+2.00
-0.00
13.0+0.50
-0.20
1.5+0.10
-0.00
1.5 MIN. 20.2 MIN. 8.0±0.30 1.75±0.10 3.5±0.05
1.0 MIN.
0.6+0.00
-0.40
3.20±0.20 3.10±0.20 1.50±0.20
2012.04 Ver.C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
(mm)
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Preliminary GR8837E
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.
2012.04 Ver.C.Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
13
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