ml4863 ETC-unknow, ml4863 Datasheet

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ml4863

Manufacturer Part Number
ml4863
Description
High Efficiency Flyback Controller
Manufacturer
ETC-unknow
Datasheet

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Part Number
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Part Number:
ml4863CS
Manufacturer:
MICROLINEAR
Quantity:
20 000
GENERAL DESCRIPTION
The ML4863 is a flyback controller designed for use in
multi-cell battery powered systems such as PDAs and
notebook computers. The flyback topology is ideal for
systems where the battery voltage can be either above or
below the output voltage, and where multiple output
voltages are required.
The ML4863 uses the output voltage as the feedback
control signal to the current mode variable frequency
flyback controller. In addition, a synchronous rectifier
control output is supplied to provide the highest possible
conversion efficiency (greater than 85% efficiency over a
1mA to 1A load range).
The ML4863 has been designed to operate with a
minimum number of external components to optimize
space and cost.
BLOCK DIAGRAM
3
1
4
SHDN
V IN
V FB
R gm
4.5V
LDO
I
18mV
18mV
BIAS & UVLO
+
+
COMP
COMP
COMPARATOR
COMPARATOR
CURRENT
RECTIFIER
High Efficiency Flyback Controller
V FB
V CC
SWITCHING
BLANKING
CONTROL
FEATURES
*Some Packages Are Obsolete
Variable frequency current mode control and
synchronous rectification for high efficiency
Minimum external components
Guaranteed start-up and operation over a wide input
voltage range (3.15V to 15V)
High frequency operation (>200kHz) minimizes the
size of the magnetics
Flyback topology allows multiple outputs in addition to
the regulated 5V
Built-in overvoltage and current limit protection
+
A2
A1
V CC
V CC
V REF
CROSS-CONDUCTION
PROTECTION
V FB
OUT 1
OUT 2
SENSE
GND
V CC
ML4863*
5
8
6
7
2
July 2000
1

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ml4863 Summary of contents

Page 1

... GENERAL DESCRIPTION The ML4863 is a flyback controller designed for use in multi-cell battery powered systems such as PDAs and notebook computers. The flyback topology is ideal for systems where the battery voltage can be either above or below the output voltage, and where multiple output voltages are required. ...

Page 2

... Secondary side current sense 3 SHDN Pulling this pin high initiates a shutdown mode to minimize battery drain 4 V Feedback input from transformer FB secondary, and supply voltage when V > 4.5V OUT 2 ML4863 8-Pin SOIC (S08 GND SENSE 2 7 OUT 2 SHDN 3 6 OUT ...

Page 3

... Lead Temperature (Soldering 10 Sec.) ..................... 260ºC Thermal Resistance ( OPERATING CONDITIONS GND – 0.3V to 18V Temperature Range GND – 0. ML4863CS ................................................. 0ºC to 70ºC ML4863ES ............................................. –20ºC to 70ºC ML4863IS .............................................. –40ºC to 85ºC V Operating Range ................................... 3.15V to 15V IN = Operating Temperature Range (Note 1) A CONDITIONS V ...

Page 4

... ML4863 ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER SUPPLY I V Quiescent Current Shutdown Current Output Voltage CC CC Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst case test conditions. 4 (Continued) CONDITIONS SHDN = 5V SHDN = 5V, V < 0V 15V 0.1µF ...

Page 5

... TRANSCONDUCTANCE AMPLIFIER + – V REF ML4863 Figure 1. Schematic of the ML4863 Controller and Power Stage TRANSCONDUCTANCE AMPLIFIER The feedback transconductance amplifier generates a ). Consequently, current from the voltage difference between the output FB and the reference. This current produces a voltage across R that adds to the negative voltage on the current sense ...

Page 6

... ML4863 FUNCTIONAL DESCRIPTION SYNCHRONOUS RECTIFIER CONTROL The control circuitry for the synchronous rectifier does not influence the operation of the main controller. The synchronous rectifier is turned on during the minimum off time, or whenever the SENSE pin is less than –18mV. During transitions where the primary switch is turned on before the voltage on the SENSE pin goes above – ...

Page 7

... Determine the minimum inductor current rating required. ( PEAK " OUT IN MIN ( ) ( ML4863 Part Number Dale LRC Series (402) 563-6506 IRC WSL Series (512) 992-7900 Coilcraft R4999 (847) 639-6400 Coiltronics OCTA-PAC Series (561)241-7876 Dale LPE-6562 Series (605) 665-9301 LPT-4545 series ...

Page 8

... Good PC board layout practices will ensure the proper operation of the ML4863. Important layout considerations follow: • The connection from the current sense resistor to the SENSE pin of the ML4863 should be made by a separate trace and connected right at the sense resistor lead. • The V ...

Page 9

... LPE-6562-A145 7 9 1,5 6, NDS9955 Q1A Q1B Q2A Q2B R1 120m GND R2 30m 1µF R3 50V 60m Figure 5. Typical PC Board Layout ML4863 12V C5 33µF 20V 100µF 100µF 100µF 100µF 6.3V 6.3V 6.3V 6.3V 8 C10 C11 C12 C13 100µF 100µ ...

Page 10

... PART NUMBER ML4863CS ML4863ES ML4863IS (Obsolete) © Micro Linear 1997 registered trademark of Micro Linear Corporation. All other trademarks are the property of their respective owners. Products described herein may be covered by one or more of the following U.S. patents: 4,897,611; 4,964,026; 5,027,116; 5,281,862; 5,283,483; 5,418,502; ...

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