IP2845A中文资料

LAB

IP1845A SERIES

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 CURRENT MODE REGULATING PULSE WIDTH MODULATORS

FEATURES

?Guaranteed ±1% reference voltage tolerance ?Accurate oscillator discharge current ?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 IP and UC1844/5 series 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)

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 IP1844A -55 to +125°C IP2844A -25 to +85°C IP3844A 0 to +70°C IP1845A -55 to +125°C IP2845A -25 to +85°C IP3845A

0 to +70°C

Order Information

Note:

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

IP1844AD–14IP3845AJ

LAB

IP1845A SERIES

V CC Supply Voltage 1I O

Output Current Analog Inputs

(pins 2 and 3)

Error Amp Output Sink Current IP1844A , IP1845A Operating Ambient Temperature Range

IP2844A , IP2845A IP3844A , IP3845A

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

Notes:

Lower limit set by under voltage lockout specification.

RECOMMENDED OPERATING CONDITIONS

* 1844A and 1845A series only.

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

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

TOGGLE FLIP FLOP *

Q DESCRIPTION

The IP1844A/IP1845A 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 the IP1844A and IP1845A series of devices have a toggle flip-flop which blanks the output on every second clock pulse, thereby ensuring that the duty cycle never exceeds 50%. For applications requiring more flexible control, all devices feature an on-chip trimmed oscillator discharge current, allowing accurate control to maximum-duty-cycle by selection of timing components. This can be beneficial even when using the IP1844A or IP1845A series, as it allows optimum safety margins to be designed into the application.

Although pin compatible with the standard IP1844/5 parts these devices offer improved performance in several areas. They also offer tighter specification and improved performance over the IP and UC1844/5 series, whilst retaining complete compatibility.

BLOCK DIAGRAM

LAB

IP1845A SERIES

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.2.Output frequency is half the oscillator frequency.

4.90

5.00 5.106206250.2

0.44.82

5.18

505

2530

160

4752570.21

51.7

7.88.38.879

2.42

2.50 2.58–0.3

–2

65900.71607026–0.5–0.85

60.7

1.1

4.95

5.00 5.056206250.2

0.44.90

5.10

505

2530

1604752570.21

51.7

7.88.38.879

2.45

2.50 2.55–0.3

–1

65900.71607026–0.5–0.85

60.7

1.1

IP1844A , IP1845A IP3844A

IP2844A , IP2845A IP3845A Parameter

Test Conditions 1Min.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 (Note 2)

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= 5V V PIN2= 2.3V R L = 15k ?V PIN2= 2.7V

R L = 15k ?

V mV mV °C V μV

mV mA

kHz %%V

V μA dB MHz dB mA V

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

REFERENCE SECTION

OSCILLATOR SECTION

ERROR AMP SECTION

All specifications apply over the full operating temperature range unless otherwise stated.(See Ordering Information for further details).

LAB

IP1845A SERIES

IP1844A , IP1845A IP3844A

IP2844A , IP2845A IP3845A Parameter

Test Conditions 1

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= 5V (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

IP1844A Series IP1845A Series IP1844A Series IP1845A Series

V PIN2= 0V IP1844A Series V PIN3= 0V IP1845A Series

I CC = 25mA

V/V V dB

μA ns

V V

ns V

V V

mA mA V

NOTES

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

CURRENT SENSE SECTION

OUTPUT SECTION

UNDER–VOLTAGE LOCKOUT SECTION

TOTAL STANDBY CURRENT

PWM SECTION

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≤0.8

For R T > 5k ?,

1.8Resultant frequency f ≈

(R T C T )

.0063 R T – 2.3

.0063 – 4

( )

t c ≈0.55 R T C T

t d ≈R T C T R n

Resultant frequency f =

(t c + t d )

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:

LAB

IP1845A SERIES

Open–Loop Laboratory Test Fixture

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

Oscillator Waveforms and Maximum Duty Cycle

GND

R T

C T

REF

V R T C

PIN4V (V for 14 pin D package)PIN7INTERNAL CLOCK

INTERNAL CLOCK

OUTPUT – Max. Duty Cycle

PIN6V (V for 14 pin D package)PIN10

PIN4

V (V for 14 pin D package)PIN7OUTPUT – Max. Duty Cycle

PIN6V (V for 14 pin D package)PIN10

LARGE C T

SMALL R T

LARGE R T SMALL C T

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IP1845A SERIES

.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

–180

0P H A S E (?

)

TYPICAL PERFORMANCE CHARACTERISTICS

1510

0.50105

52.57.510

UNDER VOLTAGE LOCKOUT

1844A SERIES

UNDER VOLTAGE LOCKOUT

1845A SERIES

V (V)CC

I (m A )

C C 20

0.5

I (m A )

C C