Microsemi UC3845AM, UC3845ADM, UC3844AM, UC3844ADM, UC3845AD Datasheet

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LIN D O C #: 1840

 

 

 

 

 

 

 

 

 

UC184xA/284xA/384xA

 

 

 

 

 

 

 

 

 

C U R R E N T M O D E P W M C O N T R O L L E R

 

 

 

 

 

 

 

T H E I N F I N I T E P O W E R O F I N N O V A T I O N

P R O D U C T I O N D A T A S H E E T

 

 

D E S C R I P T I O N

The UC184xA family of control ICs provides all the necessary features to implement off-line fixed-frequency, current-mode switching power supplies with a minimum of external components. The current mode architecture demonstrates improved load regulation, pulse-by-pulse current limiting and inherent protection of the power supply output switch. The IC includes: A bandgap reference trimmed to ±1% accuracy, an error amplifier, a current sense comparator with internal clamp to 1V, a high current totem pole output stage for fast switching of power

MOSFET's, and an externally programmable oscillator to set frequency and maximum duty cycle. The undervoltage lock-out is designed to operate with 250µA typ. start-up current, allowing an efficient bootstrap supply voltage design. Available options for this family of products, such as start-up voltage hysteresis and duty cycle, are summarized below in the Available Options section. The UC184xA family of control ICs is also available in 14-pin SOIC package which makes the Power Output Stage Collector and Ground pins available.

P R O D U C T H I G H L I G H T

COMPARISON OF UC384XA VS. SG384X DISCHARGE CURRENT

K E Y F E AT U R E S

LOW START-UP CURRENT. (0.5mA max.)

TRIMMED OSCILLATOR DISCHARGE CURRENT. (See Product Highlight)

pOPTIMIZED FOR OFF-LINE AND DC-TO-DC CONVERTERS.

pAUTOMATIC FEED FORWARD COMPENSATION.

pPULSE-BY-PULSE CURRENT LIMITING.

pENHANCED LOAD RESPONSE CHARACTERISTICS.

pUNDER-VOLTAGE LOCKOUT WITH HYSTERESIS.

pDOUBLE PULSE SUPPRESSION.

pHIGH-CURRENT TOTEM POLE OUTPUT.

pINTERNALLY TRIMMED BANDGAP REFERENCE.

p500KHz OPERATION.

pLOW RO ERROR AMPLIFIER.

 

UC384xA

SG384x

SG384x

Min. Limit

Max. Limit

 

TA=25°C

7.5

7.8

8.3

8.8

9.3

 

−3σ

Mean

+3σ

 

Discharge Current Distribution - mA

A P P L I C AT I O N S

ECONOMICAL OFF-LINE FLYBACK OR FORWARD CONVERTERS.

DC-DC BUCK OR BOOST CONVERTERS.

LOW COST DC MOTOR CONTROL.

A V A I L A B L E

O P T I O N S

 

 

 

 

 

 

 

 

 

 

Part #

 

Start-Up

Hysteresis

 

Max. Duty

 

 

 

Voltage

 

 

Cycle

 

UCx842A

 

16V

 

 

6V

 

<100%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

UCx843A

 

8.4V

 

 

0.8V

 

<100%

 

 

 

 

 

 

 

 

 

 

UCx844A

 

16V

 

 

6V

 

<50%

 

 

 

 

 

 

 

 

 

 

UCx845A

 

8.4V

 

 

0.8V

 

<50%

 

 

 

 

 

 

 

 

 

PA C K A G E O R D E R I N F O R M AT I O N

TA (°C)

M

Plastic DIP

 

DM

Plastic SOIC

D

Plastic SOIC

 

Y

Ceramic DIP

 

 

 

8-pin

 

 

8-pin

 

14-pin

 

 

8-pin

 

 

 

 

 

 

 

 

 

 

 

 

 

0 to 70

 

UC384xAM

 

 

UC384xADM

 

UC384xAD

 

 

-40 to 85

 

UC284xAM

 

 

UC284xADM

 

UC284xAD

 

 

UC284xAY

-55 to 125

 

 

 

 

 

 

UC184xAY

 

 

 

 

 

 

 

 

 

 

 

 

 

Note: All surface-mount packages are available in Tape & Reel. Append the letter "T" to part number. (i.e. UC3842ADMT)

 

F O R F U R T H E R I N F O R M AT I O N C A L L ( 7 1 4 ) 8 9 8 - 8 1 2 1

 

Copyright © 1995

 

 

11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841

1

Rev. 1.2 12/95

Microsemi UC3845AM, UC3845ADM, UC3844AM, UC3844ADM, UC3845AD Datasheet

P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7

UC184xA/284xA/384xA

C U R R E N T M O D E P W M C O N T R O L L E R

P R O D U C T I O N D A T A S H E E T

ABSOLUTE MAXIMUM RATINGS

(Note 1)

Supply Voltage (Low Impedance Source) (VCC) .........................................................

30V

Supply Voltage (ICC < 30mA)..........................................................................

Self Limiting

Output Current .............................................................................................................

±1A

Output Energy (Capacitive Load).................................................................................

5µJ

Analog Inputs (VFB & ISENSE) ........................................................................

-0.3V to +6.3V

Error Amp Output Sink Current ...............................................................................

10mA

Power Dissipation at TA = 25°C (M Package) ..............................................................

1W

Storage Temperature Range ....................................................................

-65°C to +150°C

Lead Temperature (Soldering, 10 Seconds) .............................................................

300°C

Note 1. Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal. Pin numbers refer to DIL packages only.

THERMAL DATA

M PACKAGE:

THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA

95°C/W

DM PACKAGE:

 

THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA

165°C/W

D PACKAGE:

 

THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA

120°C/W

Y PACKAGE:

 

THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA

130°C/W

Junction Temperature Calculation: TJ = TA + (PD x θJA).

The θJA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow

PACKAGE PIN OUTS

COMP

 

1

8

 

VREF

 

 

VFB

 

2

7

 

VCC

 

 

 

 

ISENSE

 

3

6

 

OUTPUT

 

 

 

 

RT/CT

 

4

5

 

GND

 

 

 

 

M & Y PACKAGE

(Top View)

COMP

 

 

 

1

8

 

 

VREF

 

 

 

 

VFB

 

 

 

2

7

 

 

VCC

 

 

 

 

 

 

 

 

ISENSE

 

 

 

3

6

 

 

OUTPUT

 

 

 

 

 

 

 

 

RT/CT

 

 

 

4

5

 

 

GND

 

 

 

 

 

 

 

 

DM PACKAGE

(Top View)

COMP

 

 

 

1

14

 

 

VREF

 

 

 

 

 

N.C.

 

 

 

2

13

 

 

N.C.

 

 

 

 

VFB

 

 

 

3

12

 

 

VCC

 

 

 

 

 

 

 

 

N.C.

 

 

 

4

11

 

 

VC

 

 

 

 

ISENSE

 

 

 

5

10

 

 

OUTPUT

 

 

 

 

N.C.

 

 

 

6

9

 

 

GND

RT/CT

 

 

 

7

8

 

 

PWR GND

 

 

 

 

 

 

 

 

D PACKAGE

(Top View)

2

 

Copyright © 1995

 

Rev. 1.2 12/95

 

 

 

P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7

UC184xA/284xA/384xA

C U R R E N T M O D E P W M C O N T R O L L E R

P R O D U C T I O N D A T A S H E E T

E L E C T R I C A L C H A R A C T E R I S T I C S

(Unless otherwise specified, these specifications apply over the operating ambient temperatures for UC384xA with 0°C TA 70°C, UC284xA with -40°C TA 85°C, UC184xA with -55°C TA 125°C; VCC=15V; RT=10K; CT=3.3nF. Low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the ambient temperature.)

Parameter

Symbol

Test Conditions

UC184xA/284xA

UC384xA

Units

Min. Typ. Max. Min. Typ. Max.

Reference Section

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Output Voltage

VREF

TJ = 25°C, IL = 1mA

4.95

5.00

5.05

4.90

5.00

5.10

V

Line Regulation

 

12 VIN 25V

 

6

20

 

6

20

mV

Load Regulation

 

1 IO 20mA

 

6

25

 

6

25

mV

Temperature Stability (Note 2 & 7)

 

 

 

0.2

0.4

 

0.2

0.4

mV/°C

Total Output Variation

 

Over Line, Load, and Temperature

4.9

 

5.1

4.82

 

5.18

V

Output Noise Voltage (Note 2)

VN

10Hz f 10kHz, TJ = 25°C

 

50

 

 

50

 

µV

Long Term Stability (Note 2)

 

TA = 125°C, t = 1000hrs

 

5

25

 

5

25

mV

Output Short Circuit Current

ISC

 

-30

-100

-180

-30

-100

-180

mA

Oscillator Section

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Initial Accuracy (Note 6)

 

TJ = 25°C

47

52

57

47

52

57

kHz

Voltage Stability

 

12 VCC 25V

 

0.2

1

 

0.2

1

%

Temperature Stability (Note 2)

 

TMIN TA TMAX

 

5

 

 

5

 

%

Amplitude (Note 2)

 

 

 

1.7

 

 

1.7

 

V

Discharge Current

 

TJ = 25°C, VPIN 4 = 2V

7.8

8.3

8.8

7.8

8.3

8.8

mA

 

 

VPIN 4 = 2V, TMIN TA TMAX

7.5

 

8.8

7.6

 

8.8

mA

Error Amp Section

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Input Voltage

 

VPIN 1 = 2.5V

2.45

2.50

2.55

2.42

2.50

2.58

V

Input Bias Current

IB

 

 

-0.3

-1

 

-0.3

-2

µA

Open Loop Gain

AVOL

2 VO 4V

65

90

 

65

90

 

dB

Unity Gain Bandwidth (Note 2)

UGBW

Tj = 25°C

0.7

1

 

0.7

1

 

MHz

Power Supply Rejection Ratio (Note 3)

PSRR

12 VCC 25V

60

70

 

60

70

 

dB

Output Sink Current

IOL

VPIN 2 = 2.7V, VPIN 1 = 1.1V

2

6

 

2

6

 

mA

Output Source Current

IOH

VPIN 2 = 2.3V, VPIN 1 = 5V

-0.5

-0.8

 

-0.5

-0.8

 

mA

Output Voltage High Level

VOH

VPIN 2 = 2.3V, RL = 15K to ground

5

6

 

5

6

 

V

Output Voltage Low Level

VOL

VPIN 2 = 2.7V, RL = 15K to VREF

 

0.7

1.1

 

0.7

1.1

V

Current Sense Section

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Gain (Note 3 & 4)

AVOL

 

2.85

3

3.15

2.85

3

3.15

V/V

Maximum Input Signal (Note 3)

 

VPIN 1 = 5V

0.9

1

1.1

0.9

1

1.1

V

Power Supply Rejection Ratio (Note 3)

PSRR

12 VCC 25V

 

70

 

 

70

 

dB

Input Bias Current

IB

 

 

-2

-10

 

-2

-10

µA

Delay to Output (Note 2)

Tpd

VPIN 3 = 0 to 2V

 

150

300

 

150

300

ns

Output Section

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Output Low Level

VOL

ISINK = 20mA

 

0.1

0.4

 

0.1

0.4

V

 

ISINK = 200mA

 

1.5

2.2

 

1.5

2.2

V

Output High Level

VOH

ISOURCE = 20mA

13

13.5

 

13

13.5

 

V

 

ISOURCE = 200mA

12

13.5

 

12

13.5

 

V

Rise Time (Note 2)

TR

TJ = 25°C, CL = 1nF

 

50

150

 

50

150

ns

Fall Time (Note 2)

TF

TJ = 25°C, CL = 1nF

 

50

150

 

50

150

ns

UVLO Saturation

VSAT

VCC = 5V, ISINK = 10mA

 

0.7

1.2

 

0.7

1.2

V

(Electrical Characteristics continue next page.)

Copyright © 1995

3

Rev. 1.2 12/95

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