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H6850S Schematic ( PDF Datasheet ) - Hi-Sincerity

Teilenummer H6850S
Beschreibung Novel Low Cost Green-Power PWM Controller
Hersteller Hi-Sincerity
Logo Hi-Sincerity Logo 




Gesamt 13 Seiten
H6850S Datasheet, Funktion
HI-SINCERITY
MICROELECTRONICS CORP.
Spec. No. : IC200912
Issued Date : 2009.07.15
Revised Date :
Page No. : 1/13
H6850 Series
Novel Low Cost Green-Power PWM Controller
With Low EMI Technique
Feature
z Low Cost, PWM&PFM&CRM (Cycle
Reset Mode)
z Low Start-up Current (about 3μA)
z Low Operating Current (about 1.2mA)
z Current Mode Operation
z Under Voltage Lockout (UVLO)
z Built-in Synchronized Slope
Compensation
z Built-in Low EMI Technique
z Programmable PWM Frequency
z Audio Noise Free Operation
z Leading edge Blanking on Sense input
z Constant output power limiting for
universal AC input Range
z SOT-23-6 L SOP8 and DIP-8 Pb-Free
Packaging
z Good Protection Coverage With Auto
Self-Recovery
z Compatible with SG6848 (6849) /
SG5701/SG5848/LD7535 (7550) /
OB2262 (2263)/OB22782279
z Complete Protection with
¾ Soft Clamped GATE output voltage
18.0V
¾ VDD over voltage protect 34.0V
¾ Cycle-by-cycle current limiting
¾ Output SCP (Short circuit Protection)
¾ Output OLP (Over Load Protection)
¾ High-Voltage CMOS Process with ESD
Applications
z Switching AC/DC Adaptor
z Battery Charger
z Open Frame Switching Power Supply
z Standby Power Supplies
z Set-Top Box Power Supplies
z 384X Replacement
General Description
The H68 50 is a highly integrated low cost
current mode PWM controller, which is ideal
for small power cur rent mode of of fline
AC-DC fly- back converter applic ations.
Making use of external resistors, the IC
changes the operating frequency and
automatically enters the PFM/CRM ( Cycle
Reset Mode) und er light-load/zer o-load
conditions. This can minimize standby
power consumption and achieve powe r-
saving functions. With a very lo w st art-up
current, the H685 0 could use a large value
start-up resistor (2M).
Built-in synchronized slo pe compens ation
enhances the st ability of the syste m and
avoids sub-harmonic oscillation. D ynamic
peak current limiting circuit minimizes output
power chang e caused by delay time of the
system over a universal AC input range.
Leading edge blanking circuit on current
sense input could remove the signal glitch
due to snubber circuit diode reverse
recovery and thus greatly reduces the
external component count and system cost
in the design. Cycle-by-Cycle current
limiting ensures safe operation even during
short-circuit.
Excellent EMI performance is achieved
built-in soft driver and low EMI technique.
The H68 50 offers perfect protection like
OVP(Over Voltage Prote ction)OLP(Over
Load Protection) SCP(Short circuit
protection)OTPSense Fault Protection
and OCP(Over current protection). The
H6850’s output driver is soft clamped to
maximum 18.0V to protect the power
MOSFET. H6850 is offered in SOT-23-6L,
SOT-8 and DIP-8 packages.
H6850P, H6850S,H6850NF
HSMC Product Specification
http://www.Datasheet4U.com






H6850S Datasheet, Funktion
HI-SINCERITY
MICROELECTRONICS CORP.
Spec. No. : IC200804
Issued Date : 2008.09.19
Revised Date :
Page No. : 6/13
OPERATION DESCRIPTION
Current Mode
Compared t o voltag e mode contr ol,
current mode control has a current feedback
loop. When the voltage of the Sense resistor
peak current of the primary winding reaches
the internal setting value VTH, the register
resets and the power MOSFET cuts off. So,
to detect and modulate the peak current
cycle-by-cycle could control the output of the
power supply. The current feedback has a
good linear modulation rate and a fast input
and output dynamic impact, and avoid the
pole that the output filter inductance brings
and the two-class system descends to the
one-class. So it widens the frequency range
and optimizes overload protection and short
circuit protection.
Startup Current and Under Voltage
Lockout
The startup current of H 6850 is se t to
be very l ow so that a large value startup
resistor can be used to minimize the power
loss. For AC to DC adaptor with universal
input range design, a 2 M, 1/8 W startup
resistor and a 10uF/25V VDD hold capacitor
could be used.
The turn-on and turn-off threshold of the
H6850 is designed to 14V/8.8V. During
startup, the hold-up capacitor must be
charge to 14.0V through the startup resistor.
The hysteresis is implemented to prevent
the shutdown from the voltage dip during
startup.
Internal Bias and OSC Operation
A resistor connected between RI pin
and GND pin sets the internal constant
current source to charge or discharge the
internal fixed capacitor. The charge time and
discharge time determines the internal clock
speed and the switching frequency.
Increasing the resistance will reduce the
value of the input current and reduce the
switching frequency. The relationship
between RI and PWM switching frequency
follows the below equation within the RI
allowed range.
H6850P, H6850S,H6850NF
FOSC
=
6500
RI (KΩ)
(kHz)
For example, a 100kresistor RI could
generate a 20uA constant current and a
65kHz PWM switching frequency. The
suggested operating frequency range of
H6850 is within 50KHz to 150KHz.
Green Power Operation
The pow er dissip ation of switching
mode power supply is very important in zero
load o r lig ht load co ndition. The majo r
dissipation results from conduction loss
switching loss and consume of the control
circuit. However, all of them relates to the
switching frequency. There are many
difference topologies has been implemented
in different chip. The basic operation theory
of all these approaches intends to reduce
the switching frequency under light-load or
no-load condition.
The H6850`s green power function
adapts PWMPFM and CRM combining
modulation. When RI resistor is 100kΩ, the
PWM frequency is 65kHz in medium or
heavy load operation. Through modifying
the pulse width, The H6850 could control
output voltage. The current of FB pin
increases when the load is in light condition
and the internal mode controller enters
PFM&PWM when the feedback current is
over 0.5mA. The operation frequency of
oscillator is to descend gradually. When the
feedback current is over 0.55mA, the
frequency of oscillator is invariable, namely
22kHz.
H6850 Green-Power Function
HSMC Product Specification

6 Page









H6850S pdf, datenblatt
SOT-23-6L
HI-SINCERITY
MICROELECTRONICS CORP.
Spec. No. : IC200804
Issued Date : 2008.09.19
Revised Date :
Page No. : 12/13
Symbol
A
A1
B
b
C
D
e
H
L
Dimensions In Millimeters
Min
0.700
0.000
Max
1.000
0.100
1.397
0.300
2.591
2.692
0.838
0.080
0.300
1.803
0.559
3.000
3.099
1.041
0.254
0.610
Dimensions In Inches
Min
0.028
0.000
Max
0.039
0.004
0.055
0.012
0.102
0.106
0.033
0.003
0.012
0.071
0.022
0.118
0.122
0.041
0.010
0.024
H6850P, H6850S,H6850NF
HSMC Product Specification

12 Page





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