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GR8935M Schematic ( PDF Datasheet ) - grenergy

Teilenummer GR8935M
Beschreibung Current Mode PWM Power Switch
Hersteller grenergy
Logo grenergy Logo 




Gesamt 10 Seiten
GR8935M Datasheet, Funktion
Preliminary GR8935M
Current Mode PWM Power Switch
Features
Current mode PWM
Very low startup current
Under-voltage lockout (UVLO)
Non-audible-noise green-mode control
Fixed switching frequency of 50KHz
Cycle-by-cycle peak current limiting
Internal leading-edge blanking
Internal slope compensation
Internal 5ms soft start
VCC over voltage clamp
Over-voltage protection (OVP) on VCC Pin
Over-load protection (OLP)
Applications
Switching AC/DC power battery charger
Digital camera
Open-frame SMPS
PDA power supply
Description
GR8935M integrates a PWM controller and high
voltage power MOSFET of 650V. GR8935M has the
features of very low startup current and current
mode PWM control with green-mode function at
light load. These features enable the power supply
to easily meet even the strictest power conservation
requirements. The integrated functions of GR8935M
also include the leading-edge blanking of the current
sensing, internal slope compensation, cycle-by-
-cycle peak current limiting and soft start. OCP, OVP
and OLP provide protection performance for fault
conditions. To protect the power MOSFET from
being damaged by supply over voltage, the internal
gate voltage of GR8935M is clamped at 18V.
GR8935M improves the performance and reduces
the cost of power supplies.
Ordering and Marking Information
GR8935M
Package Code
J: DIP-8
RoHS Code
G: Green (Halogen Free) Device
L : PB Free Device
DIP-8
GR8935M
X X XXX
Code 1
Code 2
Serial No.
Code 1 8
Year 2008
Code 2 1
Month Jan.
9
2009
2
Feb.
A
2010
3
Mar.
B
2011
4
Apr.
●●●
G
2016
9
Sep.
H
2017
A
Oct.
I
2018
B
Nov.
J
2019
C
Dec.
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. 10 Ver. 1E Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
1






GR8935M Datasheet, Funktion
Preliminary GR8935M
Application Information
Start-up Current
The typical start-up current is 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.
Under-voltage Lockout (UVLO)
A hysteresis UVLO comparator is implemented in
GR8935M, then the turn-on and turn-off thresholds
level are fixed at 15V and 9V respectively. This
hysteresis shown in Fig. 7 ensures that the start-up
capacitor will be adequate to supply the chip during
start-up.
minimum frequency is about 22KHz, which is
outside the audio range.
Leading-edge Blanking (LEB)
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 GR8935M. When the switch is on, a ramp
voltage is added to the sensed voltage across the
Sense, which helps to stabilize the system and
prevent sub-harmonic oscillations.
Fig. 7
Soft Start
During initial power on, GR8935M provides soft start
function. It effectively suppresses the start up peak
current to reduce the power MOSFET drain voltage
especially at high line.
Oscillator
The frequency of the oscillator is fixed internally at
about 50kHz. The maximum duty-cycle of internal
oscillator is limited about 75% to avoid the
transformer saturation.
Green Mode Operation
When the load decreases to an extent, the
frequency of the controller will decrease so as to
reduce the system power consumption. The
Over-load Protection (OLP)
The controller has over load protection function. An
internal circuit detects the load level, when the load
is larger than a threshold and the condition lasts
more than 40ms, the gate output will keep low level.
Then VCC decreases below UVLO off level, the
controller resets again.
Over-voltage Protection (OVP) on VCC
To prevent power MOSFET from being damaged,
GR8935M 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
internal HV power MOSFET.
The VCC OVP function is an auto-recovery type
protection. If OVP happens, the pulses will be
stopped and recover at the next UVLO on.
GR8935M is working in a hiccup mode.
2011. 10 Ver. 1E Copyright Grenergy OPTO, Inc. www.grenergy-ic.com
6

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