ML4812IP Micro Linear, ML4812IP Datasheet

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ML4812IP

Manufacturer Part Number
ML4812IP
Description
Power factor controller
Manufacturer
Micro Linear
Datasheet

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GENERAL DESCRIPTION
The ML4812 is designed to optimally facilitate a peak
current control boost type power factor correction system.
Special care has been taken in the design of the ML4812
to increase system noise immunity. The circuit includes a
precision reference, gain modulator, error amplifier, over-
voltage protection, ramp compensation, as well as a high
current output. In addition, start-up is simplified by an
under-voltage lockout circuit with 6V hysteresis.
In a typical application, the ML4812 functions as a
current mode regulator. The current which is necessary to
terminate the cycle is a product of the sinusoidal line
voltage times the output of the error amplifier which is
regulating the output DC voltage. Ramp compensation is
programmable with an external resistor, to provide stable
operation when the duty cycle exceeds 50%.
BLOCK DIAGRAM
16
5
1
2
3
4
6
7
8
OVP
I SENSE
GM OUT
EA OUT
EA–
I SINE
RAMP COMP
C T
R T
(Pin Configuration Shown is for DIP Version)
5V
5V
5V
+
+
GAIN MODULATOR
ERROR
AMP
+
OSC
I EA
S
R
FEATURES
* Some Packages Are End Of Life
Q
Q
Precision buffered 5V reference (±0.5%)
Current-input gain modulator reduces external
components and improves noise immunity
Programmable ramp compensation circuit
1A peak current totem-pole output drive
Overvoltage comparator helps prevent output
voltage “runaway”
Wide common mode range in current sense
comparators for better noise immunity
Large oscillator amplitude for better noise immunity
Power Factor Controller
5V
1k
LOCKOUT
VOLTAGE
UNDER
V CC
PWR GND
CLOCK
SHDN
32V
GND
V REF
OUT
V CC
10
12
11
14
13
15
9
ML4812*
April 1998
1

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ML4812IP Summary of contents

Page 1

GENERAL DESCRIPTION The ML4812 is designed to optimally facilitate a peak current control boost type power factor correction system. Special care has been taken in the design of the ML4812 to increase system noise immunity. The circuit includes a precision ...

Page 2

ML4812 PIN CONFIGURATION ML4812 16-Pin PDIP (P16) I SENSE OUT 2 15 GND EA OUT REF EA– OVP 5 12 OUT I SINE 6 11 PWR GND SHDN ...

Page 3

ABSOLUTE MAXIMUM RATINGS Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. Supply Current (I ) ............................................... 30mA CC Output Current ...

Page 4

ML4812 ELECTRICAL CHARACTERISTICS PARAMETER GAIN MODULATOR I Input Voltage SINE Output Current (GM OUT) Bandwidth PSRR OVP COMPARATOR Input Offset Voltage Hysteresis Input Bias Current Propagation Delay PWM COMPARATOR: I SENSE Input Offset Voltage Input Offset Current Input Common Mode ...

Page 5

FUNCTIONAL DESCRIPTION OSCILLATOR The ML4812 oscillator charges the external capacitor (C with a current (I ) equal to 5/R . When the capacitor SET SET voltage reaches the upper threshold, the comparator changes state and the capacitor discharges to the ...

Page 6

ML4812 FUNCTIONAL DESCRIPTION OUTPUT DRIVER STAGE The ML4812 output driver peak output high speed totem pole circuit designed to quickly drive capacitive loads, such as power MOSFET gates. (Figure 3) ERROR AMPLIFIER The ML4812 error amplifier is ...

Page 7

TYPICAL APPLICATIONS INPUT INDUCTOR (L1) SELECTION The central component in the regulator is the input boost inductor. The value of this inductor controls various critical operational aspects of the regulator. If the value is too low, the input current distortion ...

Page 8

ML4812 TYPICAL APPLICATIONS (Continued) The recommended maximum duty cycle is 95% at 100KHz to allow time for the input inductor to dump its energy to the output capacitors. For example, if: V 380V and D (max) = 0.95, then substituting ...

Page 9

TYPICAL APPLICATIONS (Continued) CURRENT SENSE AND SLOPE (RAMP) COMPENSATION COMPONENT SELECTION Slope compensation in the ML4812 is provided internally. Rather than adding slope to the noninverting input of the PWM comparator actually subtracted from the voltage present at ...

Page 10

ML4812 TYPICAL APPLICATIONS (Continued) Choose 4.75k , 1%. One more critical component in the voltage regulation loop is the feedback capacitor for the error amplifier. The voltage loop bandwidth should be set such that it rejects the 120Hz ripple which ...

Page 11

TYPICAL APPLICATIONS (Continued) MATERIAL MANUFACTURER Powdered Iron Powdered Iron Molypermalloy SPANG (Mag. Inc.) MAGNETICS TIPS L1 — Main Inductor As shown in Table 1, one of several toroidal cores can be used for L1. The T184-40 core above is the ...

Page 12

ML4812 Figure 12. Typical Application, 200W Power Factor Correction Circuit 12 ...

Page 13

... Ceramic T D1, D2, D3, D4, D10 1N5406 (Motorola) D5 MUR850 (Motorola) D6, D8, D9 1N4148 D11, D12, D13 F1 5A, 250V 3AG with clips IC1 ML4812CP (Micro Linear) L1 2mH PEAK Q1 IRF840 or MTPN8N50 Q2 LM7815CT Q3 2N2222 or equivalent Table 2. Component Values/Bill of Materials for Figure 12 REFERENCE R1A, R1B, R4A, R4B ...

Page 14

ML4812 + Figure 13. 1kW Input Power, Power Factor Correction Circuit 14 ...

Page 15

PHYSICAL DIMENSIONS 16 PIN 0.02 MIN (0.50 MIN) (4 PLACES) 0.170 MAX (4.32 MAX) 0.125 MIN (3.18 MIN) 0.385 - 0.395 (8.89 - 10.03) 0.350 - 0.356 (8.89 - 9.04) 1 PIN 1 ID 0.042 - 0.048 ...

Page 16

... ORDERING INFORMATION PART NUMBER ML4812CP ML4812CQ ML4812IP ML4812IQ © Micro Linear 1998 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; ...

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