Texas Instruments UC3854BQ, UC3854BN, UC3854BDWTR, UC3854BDW, UC3854AN Datasheet

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BLOCK DIAGRAM

• Controls Boost PWM to Near Unity
Power Fac tor

• Limits Line Current Distortion To <3%

• World-Wide Operation Without Switches

• Accurate Power Limiting

• Fixed Frequency Average Current Mode

Control

• High Bandwidth (5MHz), Low Offset
Current Am p lifier

• Integrated Current and Voltage Amp
Output Clamps

• Multiplier Improvem ents: Linearity,
500mV VAC Offset (eliminates external
resistor), 0-5V Multout Common Mode
Range

• V

REF

"GOOD" Comparator

• Faster and Improved Accuracy ENABLE
Comparator

• UVLO Threshold Options
(16/10V / 10.5/10V)

• 300µA Startup Supply Current

The UC1854A/B pro duct s are pin compatible enhan ced versi ons of the
UC1854. Li ke the UC1854, these pr oducts prov ide all of the functions
necessary for active power factor corrected preregulators. The
controller achieves near unity power factor by shaping the AC input line
current wav ef or m to corres pond to the AC input line voltage. To do this
the UC185 4A/B uses a verage current mode control. Average c urrent
mode control maintains stable, low distortion sinusoidal line current
without the need for slope compensation, unlike peak current mode
control.

The UC1854A/B products i mprove upon t he UC 1854 by offering a wide
bandwidth, low offset Current Amplifier, a faster responding and
improved accuracy enable comparator, a V

REF

"good" comparator,
UVLO thresh old options (16/ 10V for offline, 10.5/10V for startup from
an auxiliary 12V regulator), lower startup supply current, and an
enhanced m ultiply/ divide circui t. New featu res like the ampli fier output
clamps, improved amplifier current sinking capability, and low offset
VAC pin reduce the external component count while improving
performance. Improved common mode input range of the Multiplier
output/Current Amp input allow the designer greater flexibility in
choosing a method for current sensing. U nlike its pre decessor, R

SET

controls onl y oscillator charging curr ent and has no effect on clamping
the maximum multiplier output curr ent. This current is no w clamped to
a maximu m of 2 * IAC at all t imes which simplifies the desi gn process
and pro vides foldb ack power lim iting dur ing brow nout and extrem e low
line conditions.

A 1% 7.5V reference, fixed frequency oscillator, PWM, Voltage
Amplifier w ith softstar t, line voltage feedforwar d (V

RMS

squarer) , input
supply vol tage clamp, and over current com par ator roun d out the list of
features.

UC1854A/B
UC2854A/B
UC3854A/B

Enhanced High Power Factor Preregulator

FEATURES

DESCRIPTION

UVLO Turn on UVLO Turn off

UC1854A 16V 10V
UC1854B 10.5V 10V

UDG-93001-1

DIL–16 & SOIC-16
(Top V ie w )
J, N & DW Packages

PACKAGE PIN FUNCTION

FUNCTION PIN

N/C 1
Gnd 2
PKLMT 3
CA Out 4
I

SENSE

5
N/C 6
Mult Out 7
I

AC

8
VA Out 9
V

RMS

10
N/C 11
V

REF

12
ENA 13
V

SENSE

14
R

SET

15
N/C 16
SS 17
C

T

18
V

CC

19
GT Drv 20

PLCC-20 & LCC-20
(Top View)
Q & L Packages

CONNECTION DIAGRAMS

Supply Voltage VCC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22V

GT Drv Current, Continuous. . . . . . . . . . . . . . . . . . . . . . . 0.5A

GT Drv Current, 50% Duty Cycle. . . . . . . . . . . . . . . . . . . . 1.5A

Input Voltage, V

SENSE

, V

RMS

. . . . . . . . . . . . . . . . . . . . . . . 11V

Input Voltage, I

SENSE

, Mult Out . . . . . . . . . . . . . . . . . . . . . 11V

Input Voltage, PKLMT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5V

Input Current, R

SET

, IAC, PKLMT, ENA . . . . . . . . . . . . . . 10mA

Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1W

Storage Temperature . . . . . . . . . . . . . . . –65°C to +150°C

Lead Temperature (Soldering, 10 Seconds) . . . . . . . . . +300°C

ABSOLUTE MAXIMUM RATINGS

UC1854A/B
UC2854A/B
UC3854A/B

Note 1: All voltages with respect to Gnd (Pin 1).
Note 2: All currents are positive into the specified terminal.
Note 3: ENA imput is internally clamped to approximately 10V.
Note 4: Consult Unitrode Integrated Circuits databook for
information regarding thermal specifications and limitations of
packages.

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

OVERALL

Supply Current, Off CAO, VAO = 0V, VCC = UVLO - 0.3V 250 400 µA
Supply Current, On 12 18 mA
VCC Turn-On Threshold UC1854A 16 17.5 V

UC1854B 10.5 11.2 V
VCC Turn-Off Threshold UC1854A / B 9 10 V
V

CC

Clamp I(VCC) = ICC(on) + 5mA 18 20 22 V

VOLTAGE AMPLIFIER

Input Voltage 2.9 3.0 3.1 V
V

SENSE

Bias Current –500 –25 500 nA

Open Loop Gain V

OUT

= 2 to 5V 70 100 dB

V

OUT

High I

LOAD

= –500µA6V

V

OUT

Low I

LOAD

= 500µA 0.3 0.5 V

Output Short Circuit Current V

OUT

= 0V 1.5 3.5 mA

Gain Bandwidth Product Fin = 100kHz, 10mV p-p, (Note 1) 1 mHz

Unless otherwise stated, V

CC

=18V, RT=8.2k, CT=1.5nF, PKLMT=1V, V

RMS

=1.5V,

I

AC

=100µA, I

SENSE

=0V, CA Out=3.5V, VA Out=5V, V

SENSE

=3V, –55oC<TA<125oC

for the UC1854A/B, –40

o

C<TA<85oC for the UC2854A/B, and 0oC<TA<70oC for the

UC3854A/B, and T

A=TJ

.

ELECTRICAL CHARACTERISTICS

2

ELECTRICAL
CHARACTERISTICS (cont.)

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

CURRENT AMPLIFIER

Input Offset Voltage V

CM

= 0V TA = +25°C −40mV

OverTemp –5.5 0 mV
Input Bias Current(sense) VCM = 0V –500 500 nA
Open Loop Gain VCM = 0V, V

OUT

= 2 to 6V 80 110 dB

V

OUT

High I

LOAD

= –500µA8V

V

OUT

Low ILOAD = 500µA 0.3 0.5 V

Output Short Circuit Current V

OUT

= 0V 1.5 3.5 mA
Common Mode Range –0.3 5 V
Gain Bandwidth Product Fin = 100kHz, 10mV p-p, (Note 1) 3 5 mHz

REFERENCE

Output Voltage I

REF

= 0mA, TA = 25oC 7.4 7.5 7.6 V

I

REF

= 0mA 7.35 7.5 7.65 V

Load Regulation I

REF

= 1 to 10mA 0 8 20 mV

Line Regulation V

CC =

12 to 18V 0 14 25 mV
Short Circuit Current V

REF

= 0V 25 35 60 mA

OSCILLATOR

Initial Accuracy TA = 25oC 85 100 115 kHz
Voltage Stability V

CC =

12 to 18V 1 %
Total Variation Line, Temp 80 120 kHz
Ramp Amplitude (p-p) 4.9 5.9 V
Ramp Valley Voltage 0.8 1.3 V

ENABLE / SOFTSTART / CURRENT LIMIT

Enable Threshold 2.35 2.55 2.8 V
Enable Hysteresis V

FAULT

= 2.5V 500 600 mV

Enable Input Bias Current V

ENABLE

= 0V –2 –5 µA
Propagation Delay to Disable Enable Overdrive = –100mV,(Note 1) 300 ns
SS Charge Current V

SOFTSTART

= 2.5V 10 14 24
PKLMT Offset Voltage –15 15 mV
PKLMT Input Current V

PKLMT

= –0.1V –200 –100 µA

PKLMT Propagation Delay (Note 1) 150 ns

MULTIPLIER

Output Current - IAC Limited IAC=100µA, V

RMS

= 1V, R

SET

= 10k –220 –200 –170 µA

Output Current - Zero IAC=0µA, R

SET

= 10k –2.0 –0.2 2.0 µA

Output Current - Power Limited V

RMS

= 1.5V, Va = 6V –230 –200 –170 µA

Output Current V

RMS

= 1.5V, Va = 2V –22 µA

V

RMS

= 1.5V, Va = 5V –156 µA

V

RMS

= 5V, Va = 2V –2 µA

V

RMS

= 5V, Va = 5V –14 µA

Gain Constant (Note 2) V

RMS

= 1.5V, TJ = 25°C, Va = 6V –1.1 –1.0 –0.9 A/A

UC1854A/B
UC2854A/B
UC3854A/B

Unless otherwise stated, VCC=18V, RT=8.2k, CT=1.5nF, PKLMT=1V, V

RMS

=1.5V,

I

AC

=100µA, I

SENSE

=0V, CA Out=3.5V, VA Out=5V, V

SENSE

=3V, –55oC<TA<125oC for the

UC1854A/B, –40

o

C<TA<85oC for the UC2854A/B, and 0oC<TA<70oC for the UC3854A/B,

and T

A=TJ

.

Note 1: Guaranteed by design, not 100% tested in production.
Note 2: Gain constant (K) =

I

AC

× (Va − 1.5

V

)

V

RMS

2 ×

I

MO

3