IP2845中文资料

LAB

IP1845 SERIES

CURRENT MODE REGULATING PULSE WIDTH MODULATORS

FEATURES

?Guaranteed ±1% reference voltage tolerance ?Guaranteed ±10% frequency tolerance ?Low start–up current (<500 m A)

?Under voltage lockout with hysteresis

Output state completely defined for all supply and input conditions

?Interchangeable with UC1844 and UC1845series for improved operation ?500kHz Oscillator operation 250kHz Output operation

+30V Self limiting

±1A 5μJ

–0.3V to +V CC

10mA 1W 10mW/°C 725mW 7.25mW/°C

2W 16mW/°C –65 to 150°C +300°C

ABSOLUTE MAXIMUM RATINGS (T case = 25°C unless otherwise stated)

TOP VIEW

J Package – 8 Pin Ceramic DIP N Package – 8 Pin Plastic DIP

D-8 Package – 8 Pin Plastic (150) SOIC

234

8765

COMP V REF GROUND

OUTPUT R T /C T V CC I SENSE V FB TOP VIEW

D-14 Package – 14 Pin Plastic (150) SOIC

COMP V REF GROUND OUTPUT 12

POWER GROUND

141312111098

N/C

R T /C T I SENSE N/C

N/C

N/C V CC V FB V C V CC Supply Voltage

(low impedance source)(I CC < 30mA)I O

Output Current Output Energy (capacitive load)Analog Inputs

(pins 2 and 3)Error Amp Output Sink Current P D Power Dissipation

T amb = 25°C J, N Packages Derate @ T amb > 50°C P D Power Dissipation

T case = 25°C D Package Derate @ T amb > 50°C P D Power Dissipation

T case = 25°C

J, N Packages

Derate @ T case > 25°C

T STG Storage Temperature Range T L

Lead Temperature

(soldering, 10 seconds)

Part J–Pack N–Pack

D–8D–14Temp.Number 8 Pin 8 Pin 8 Pin 14 Pin Range IP1844 -55 to +125°C IP2844 -25 to +85°C IP3844 0 to +70°C IP1845 -55 to +125°C IP2845 -25 to +85°C IP3845

0 to +70°C

Order Information

Note:

To order, add the package identifier to the part number.eg.

IP1844D–14IP3845J

LAB

IP1845 SERIES

DESCRIPTION

The IP1844 and IP1845 series of switching regulator control circuits contain all the functions necessary to implement off-line, current mode switching regulators, using a minimum number of external parts.

Functions included are voltage reference, error amplifier, current sense comparator, oscillator, totem-pole output driver and under-voltage lockout circuitry. In addition there is a toggle flip-flop which blanks the output on every second clock pulse, thereby ensuring that the duty cycle never exceeds 50%.

Although pin compatible with the UC1844 and UC1845 series, SEMELAB has incorporated several improvements in the IP1844 and IP1845 series allowing tighter and more complete specification of electrical performance .

BLOCK DIAGRAM

Values in brackets are for IP1845 series.3.6V

ERROR AMP

OSCILLATOR

2R R

S PWM LATCH CURRENT SENSE

COMPARATOR

16V (8.4V)

6V (0.5V)

2.5V

UNDER–VOLTAGE

LOCKOUT

ENABLE

REFERENCE REGULATOR

5V INTERNAL BIAS

34V

REG

S V STATUS LATCH

REF

Q TOGGLE FLIP FLOP

PIN NUMBERS

1st Number 2nd Number – N, J and 8 Pin D Packages – 14 Pin D Package.

C OMP G ND

V CC

I SENSE

V FB /C R T

T OUTPUT

POW ER GROUND

V REF

V C

3/5

5/9

7/12

2/31/1

4/7

6/10

7/11

5/8

8/14

V CC Supply Voltage I O

Output Current Analog Inputs

(pins 2 and 3)

Error Amp Output Sink Current IP1844 , IP1845Operating Ambient Temperature Range

IP2844 , IP2845IP3844 , IP3845

≤ 30V 0 to ±200mA –0.3V to 3V 0 to 2mA –55 to 125°C –25 to 85°C 0 to 70°C

RECOMMENDED OPERATING CONDITIONS

LAB

IP1845 SERIES

4.90

5.00 5.106206250.2

0.44.82

5.18

505

2530

160

4752570.21

51.78.38

2.42 2.50 2.58–0.3

–2

65900.71607026–0.5–0.85.0

6.00.7

1.1

4.95

5.00 5.056206250.2

0.44.90

5.10

505

2530

1604752570.21

51.78.38

2.45 2.50 2.55–0.3

–1

65900.71607026–0.5–0.85.0

6.00.7

1.1

IP1844/IP1845IP3844

IP2844/IP2845IP3845Parameter

Test Conditions Min.Typ.Max.Min.Typ.Max.Units Output Voltage Input Regulation Output Regulation Temperature Stability Total Output Variation Output Noise Voltage Long Term Stability Output Short Circuit Current Frequency Voltage stability Temperature Stability Amplitude Discharge Current

Input Voltage Input Bias Current Open Loop Voltage Gain

Unity Gain Bandwidth Supply Voltage Rejection

Output Sink Current Output Source Current V OUT High V OUT Low

I O = 1mA T J = 25°C

V CC = 12V to 25V I O = 1mA to 20mA

Line, Load, Temp f = 10Hz to 10kHz

T J = 25°C

T J = 125°C @ 1000Hrs V REF = 0

T J = 25°C V CC = 12V to 25V ?T A = Min to Max V PIN4Peak to Peak T J = 25°C ?T A = Min to Max

V PIN1= 2.5V

V O = 2V to 4V V CC = 12V to 25V V PIN2= 2.7V V PIN1= 1.1V V PIN2= 2.3V V PIN1= 5.0V V PIN2= 2.3V R L = 15k ?V PIN2= 2.7V

R L = 15k ?

V mV mV °C V μV

mV mA

kHz %%V mA %

V μA dB MHz dB mA V

ELECTRICAL CHARACTERISTICS (Over Full Operating Temperature Range unless otherwise stated)

REFERENCE SECTION

OSCILLATOR SECTION

ERROR AMP SECTION

NOTES

1.Test Conditions unless otherwise stated:

V CC = 15V* , R T = 10k ?, C T = 3.3nF , f = 52kHz.

*Adjust V CC above start threshold before setting at required level.All specifications apply over the full operating temperature range

unless otherwise stated. (See Ordering Information for further details).

IP1844/IP1845IP3844

IP2844/IP2845IP3845Parameter

Test Conditions

Min.Typ.Max.Min.Typ.Max.Units 2.853 3.150.91 1.1

70–2–101503000.10.41.5

2.2

1313.512

13.550150501500.7 1.114.51617.57.88.498.51011.57

7.68.20.30.5111514173034404648

500

2.853

3.150.91 1.1

70–2–10150

3000.10.41.5

2.2131

3.512

13.550150501500.7

1.11516177.88.49910117

7.68.20.30.5111514

1730344047

500

Gain

Maximum Input Signal Supply Voltage Rejection Input Bias Current Delay to Output

Output Low Level Output High Level Rise Time Fall Time UVLO Saturation Upper Threshold (V CC )

Lower Threshold (V CC )

Start–up Current Operating Supply Current

V CC Zener Voltage Maximum Duty Cycle Minimum Duty Cycle

See Notes 2,3V PIN1= 5.0V (Note 2)

V C = 12V to 25V

I SINK = 20mA I SINK = 200mA I SOURCE = 20mA I SOURCE = 200mA C L = 1nF C L = 1nF V CC = 6V I L = 1mA

1844 Series 1845 Series 1844 Series 1845 Series

V PIN2= 0V 1844 Series V PIN3= 0V 1845 Series

I CC = 25mA

V/V V dB

μA ns

V V

ns V

V V

mA mA V

LAB

IP1845 SERIES

ELECTRICAL CHARACTERISTICS (Over Full Operating Temperature Range unless otherwise stated)

CURRENT SENSE SECTION

OUTPUT SECTION

UNDER–VOLTAGE LOCKOUT SECTION

PWM SECTION

NOTES

1.Test Conditions unless otherwise stated:

V CC = 15V* , R T = 10k ?, C T = 3.3nF , f = 52kHz.*Adjust V CC above start threshold before setting at required level.All specifications apply over the full operating temperature range unless otherwise stated.

(See Ordering Information for further details).

2.Parameter measured at trip point of latch with V PIN2= 0V

3.Gain defined as:

?V PIN1A =

?V PIN30 ≤V PIN3≤0.8TOTAL STANDBY CURRENT

LAB

IP1845 SERIES

APPLICATIONS INFORMATION

V - Pin 4

(Pin 7 for 14 Pin D Package)

GND

REF

V R C T T

C T

R T

Internal Clock

Output – Max. Duty Cycle V - Pin 6

(Pin 10 for 14 Pin D Package)

Output – Max. Duty Cycle V - Pin 6

(Pin 10 for 14 Pin D Package)

V - Pin 4

(Pin 7 for 14 Pin D Package)

LARGE SMALL

R T C T

LARGE

SMALL R T C T

Oscillator Waveforms and Maximum Duty Cycle

Oscillator timing capacitor C T is charged by V REF through R T and discharged by an internal current source. During the discharge time, the internal clock signal blanks the output to the low state. Selection of R T and C T therefore determines both oscillator frequency and maximum duty cycle.

Charge and discharge times are determined by the formulae:

t c ≈0.55 R T C T

t d ≈R T C T R n

Resultant frequency f =

(t c + t d )For R T > 5k ?,

1.8Resultant frequency f ≈

(R T C T )

.0063 R T – 2.3.0063 – 4

( )

LAB

IP1845 SERIES

Open–Loop Laboratory Test Fixture

.01

.02

.04.07

1.0

604020

10080

100

10k

10M

100k

.05

.03.3

OUTPUT CURRENT, SOURCE / SINK (A)

FREQUENCY (Hz)

S A T U R A T I O N V O L T A G E (V )

V O L T A G E G A I N (d B )

OUTPUT SATURATION CHARACTERISTICS

ERROR AMPLIFIER OPEN-LOOP

FREQUENCY RESPONSE

V = 15V CC

T = 25?C A

A V

SOURCE SAT V - )CC V OH

SINK SAT (V )OL

T = –55?C –45–90–135

–1800P H A S E (?)

TYPICAL PERFORMANCE CHARACTERISTICS

APPLICATIONS INFORMATION

High peak current associated with capacitive loads necessitate careful grounding techniques. Timing and bypass capacitors should be connected close to pin 5 in a single point ground. The transistor and 5K potentiometer are used to sample the oscillator wave form and apply an adjustable ramp to pin 3.

0.1μF

1k ?1kW

1k ?

ERROR AMP

ADJUST

4.7k ?

5k ?

ADJUST

4.7k ?

100k ?

2N2222I SENSE R T

C T

0.1μF

V REF V CC

OUTPUT

GROUND

1245

7836I SENSE V REF V CC O/P GND COMP V FB R T /C T

020

15100.50

1051520

020

0.5

52.57.510

UNDER VOLTAGE LOCKOUT

1844 SERIES

UNDER VOLTAGE LOCKOUT

1845 SERIES

V (V)CC

I (m A )

C C V (V)CC

I (m A )

C C