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产品型号UC2845AD8TR的概述

UC2845AD8TR芯片概述 UC2845AD8TR是一款高性能的电源管理集成电路（IC），特别设计用于开关模式电源（SMPS）的控制。它采用了高效的脉冲调制技术，以提供优异的电压控制和电流管理特性，广泛应用于电源转换器、直流-直流转换器和其他相关领域。UC2845AD8TR是由安森美半导体（ON Semiconductor）公司制造，其设计目标是为开关平均电流控制提供解决方案。 UC2845AD8TR的设计特点使其可以在宽范围的输入电压和负载条件下工作，使得它在各种应用场合中表现出色。该芯片在额定电源下能够提供稳定的输出，确保连续的电能传输与高效的能量利用。 UC2845AD8TR的详细参数 UC2845AD8TR具有一系列重要参数，这些参数为电路设计人员在选用和应用该芯片时提供了参考依据。以下是一些关键的技术参数： - 最大输入电压（VCC）: 30V - 参考电压（V_REF）...

产品型号UC2845AD8TR的Datasheet PDF文件预览

UC1842A/3A/4A/5A

UC2842A/3A/4A/5A

UC3842A/3A/4A/5A

Current Mode PWM Controller

FEATURES

DESCRIPTION

•

Optimized for Off-line and DC to DC

The UC1842A/3A/4A/5A family of control ICs is a pin for pin compat-

ible improved version of the UC3842/3/4/5 family. Providing the nec-

essary features to control current mode switched mode power

supplies, this family has the following improved features. Start up cur-

rent is guaranteed to be less than 0.5mA. Oscillator discharge is

trimmed to 8.3mA. During under voltage lockout, the output stage can

sink at least 10mA at less than 1.2V for VCC over 5V.

Converters

•

Low Start Up Current (<0.5mA)

Trimmed Oscillator Discharge Current

Automatic Feed Forward Compensation

Pulse-by-Pulse Current Limiting

Enhanced Load Response Characteristics

Under-Voltage Lockout With Hysteresis

Double Pulse Suppression

The difference between members of this family are shown in the table

below.

Maximum Duty

Part #

UVLO On

UVLO Off

Cycle

<100%

<50%

High Current Totem Pole Output

Internally Trimmed Bandgap Reference

500kHz Operation

UC1842A

UC1843A

UC1844A

UC1845A

16.0V

8.5V

10.0V

7.9V

16.0V

8.5V

10.0V

7.9V

<50%

Low RO Error Amp

BLOCK DIAGRAM

A/B

Note 1:

A = DIL-8 Pin Number. B = SO-14 Pin Number.

Note 2: Toggle flip flop used only in 1844A and 1845A.

9/94

UC1842A/3A/4A/5A

UC2842A/3A/4A/5A

UC3842A/3A/4A/5A

ABSOLUTE MAXIMUM RATINGS (Note 1)

CONNECTION DIAGRAMS

DIL-8, SOIC-8 (TOP VIEW)

J or N, D8 Package

Supply Voltage (Low Impedance Source) . . . . . . . . . . . . . . 30V

Supply Voltage (ICC mA). . . . . . . . . . . . . . . . . . . . . Self Limiting

Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A

Output Energy (Capacitive Load). . . . . . . . . . . . . . . . . . . . . 5µJ

Analog Inputs (Pins 2, 3) . . . . . . . . . . . . . . . . . . -0.3V to +6.3V

Error Amp Output Sink Current . . . . . . . . . . . . . . . . . . . . 10mA

Power Dissipation at TA ≤ 25°C (DIL-8) . . . . . . . . . . . . . . . . 1W

Storage Temperature Range . . . . . . . . . . . . . -65°C to +150°C

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

Note 1. All voltages are with respect to Ground, Pin 5. Currents

are positive into, negative out of the specified terminal. Consult

Packaging Section of Databook for thermal limitations and con-

siderations of packages. Pin numbers refer to DIL package only.

PACKAGE PIN FUNCTION

PLCC-20, LCC-20

(TOP VIEW)

Q, L Packages

FUNCTION

N/C

SOIC-14 (TOP VIEW)

D Package

Comp

N/C

VFB

3-4

N/C

ISENSE

N/C

RT/CT

N/C

Pwr Gnd

Gnd

N/C

Output

N/C

VCC

N/C

8-9

VREF

ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for -55°C ≤ TA ≤ 125°C for the

UC184xA; -40°C ≤ TA ≤ 85°C for the UC284xA; 0 ≤ TA ≤ 70°C for the UC384xA; VCC = 15V (Note 5); RT = 10k; CT = 3.3nF; TA = TJ; Pin

numbers refer to DIL-8.

UC184xA\UC284xA

UC384xA

PARAMETER

TEST CONDITIONS

UNITS

MIN. TYP. MAX. MIN. TYP. MAX.

Reference Section

Output Voltage

TJ = 25°C, IO = 1mA

4.95

4.9

5.00

5.05

4.90

4.82

5.00

5.10

Line Regulation

12 ≤ VIN ≤ 25V

Load Regulation

Temp. Stability

1 ≤ IO ≤ 20mA

(Note 2, Note 7)

0.2

0.4

5.1

0.2

0.4

5.18

mV/°C

Total Output Variation

Output Noise Voltage

Line, Load, Temp.

10Hz ≤ f ≤ 10kHz

TJ = 25°C (Note 2)

TA = 125°C, 1000Hrs. (Note 2)

µV

Long Term Stability

Output Short Circuit

Oscillator Section

Initial Accuracy

-30

-100

-180

-30

-100

-180

TJ = 25°C (Note 6)

0.2

kHz

Voltage Stability

Temp. Stability

12 ≤ VCC ≤ 25V

TMIN ≤ TA ≤ TMAX (Note 2)

VPIN 4 peak to peak (Note 2)

TJ = 25°C, VPIN 4 = 2V (Note 8)

VPIN 4 = 2V (Note 8)

Amplitude

1.7

8.3

1.7

8.3

Discharge Current

7.8

7.5

8.8

7.8

7.6

8.8

UC1842A/3A/4A/5A

UC2842A/3A/4A/5A

UC3842A/3A/4A/5A

ELECTRICAL CHARACTERISTICS (cont.) Unless otherwise stated, these specifications apply for -55°C ≤ TA ≤ 125°C for

the UC184xA; -40°C ≤ TA ≤ 85°C for the UC284xA; 0 ≤ TA ≤ 70°C for the UC384xA; VCC = 15V (Note 5); RT = 10k; CT = 3.3nF; TA = TJ;

Pin numbers refer to DIL-8.

UC184xA\UC284xA

UC384xA

PARAMETER

TEST CONDITIONS

UNITS

MIN. TYP. MAX. MIN. TYP. MAX.

Error Amp Section

Input Voltage

Input Bias Current

AVOL

VPIN 1 = 2.5V

2.45

2.50

-0.3

2.55

-1

2.42 2.50

-0.3

2.58

-2

µA

MHz

2 ≤ VO ≤ 4V

0.7

Unity Gain Bandwidth

PSRR

TJ = 25°C (Note 2)

12 ≤ VCC ≤ 25V

Output Sink Current

Output Source Current

VOUT High

VPIN 2 = 2.7V, VPIN 1 = 1.1V

VPIN 2 = 2.3V, VPIN 1 = 5V

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

VPIN 2 = 2.7V, RL = 15k to Pin 8

-0.5

-0.8

-0.5

-0.8

VOUT Low

0.7

1.1

0.7

1.1

Current Sense Section

Gain

(Note 3, Note 4)

2.85

0.9

3.15

1.1

2.85

0.9

3.15

1.1

V/V

Maximum Input Signal

PSRR

VPIN 1 = 5V (Note 3)

12 ≤ VCC ≤ 25V (Note 3)

-2

µA

Input Bias Current

Delay to Output

Output Section

Output Low Level

-10

VPIN 3 = 0 to 2V (Note 2)

150

300

150

300

ISINK = 20mA

0.1

0.4

2.2

0.1

0.4

2.2

ISINK = 200mA

Output High Level

ISOURCE = 20mA

13.5

ISOURCE = 200mA

Rise Time

TJ = 25°C, CL = 1nF (Note 2)

VCC = 5V, ISINK = 10mA

150

1.2

150

1.2

Fall Time

UVLO Saturation

Under-Voltage Lockout Section

Start Threshold

0.7

x842A/4A

x843A/5A

x842A/4A

x843A/5A

7.8

8.4

9.0

14.5

7.8

8.5

7.0

8.4

17.5

9.0

Min. Operation Voltage After

TurnOn

11.5

8.2

7.0

7.6

8.2

7.6

PWM Section

Maximum Duty Cycle

x842A/3A

x844A/5A

100

Minimum Duty Cycle

Total Standby Current

Start-Up Current

0.3

0.5

0.3

0.5

Operating Supply Current

VCC Zener Voltage

VPIN 2 = VPIN 3 = 0V

ICC = 25mA

Note 2: These parameters, although guaranteed, are not 100%

tested in production.

Note 3: Parameter measured at trip point of latch with VPIN2 = 0.

VREF (max) − VREF (min)

TJ (max) − TJ (min)

VREF (max) and VREF (min) are the maximum & mini-

mum reference voltage measured over the appropriate

temperature range. Note that the extremes in voltage

do not necessarily occur at the extremes in tempera-

ture."

Temp Stability =

∆VPIN 1

Note 4: Gain defined as: A =

; 0 ≤ VPIN 3 ≤ 0.8V.

∆VPIN 3

Note 5: Adjust VCC above the start threshold before setting at

15V.

Note 6: Output frequency equals oscillator frequency for the

UC1842A and UC1843A. Output frequency is one half

oscillator frequency for the UC1844A and UC1845A.

Note 7: "Temperature stability, sometimes referred to as average

temperature coefficient, is described by the equation:

Note 8: This parameter is measured with RT = 10kΩ to VREF.

This contributes approximately 300µA of current to the

measurement. The total current flowing into the RT/CT

pin will be approximately 300µA higher than the meas-

ured value.

UC1842A/3A/4A/5A

UC2842A/3A/4A/5A

UC3842A/3A/4A/5A

Error Amp Configuration

Error Amp can Source and Sink up to 0.5mA, and Sink up to 2mA.

Under-Voltage Lockout

During UVLO, the Output is low.

Current Sense Circuit

Peak Current (IS) is Determined By The Formula

1.0V

ISMAX ≈

A small RC filter may be required to suppress switch transients.

UC1842A/3A/4A/5A

UC2842A/3A/4A/5A

UC3842A/3A/4A/5A

APPLICATIONS DATA (cont.)

Output Saturation Characteristics

Error Amplifier Open-Loop Frequency Response

Oscillator Section

Oscillator Frequency vs Timing Resistance

Maximum Duty Cycle vs Timing Resistor

Open-Loop Laboratory Test Fixture

High peak currents associated with capacitive loads necessi-

tate careful grounding techniques. Timing and bypass capaci-

tors should be connected close to pin 5 in a single point

ground. The transistor and 5k potentiometer are used to sam-

ple the oscillator waveform and apply an adjustable ramp to

pin 3.

UC1842A/3A/4A/5A

UC2842A/3A/4A/5A

UC3842A/3A/4A/5A

APPLICATIONS DATA (cont.)

Off-line Flyback Regulator

Power Supply Specifications

5. Output Voltage:

A. +5V, ±5%; 1A to 4A load

Ripple voltage: 50mV P-P Max

B. +12V, ±3%; 0.1A to 0.3A load

Ripple voltage: 100mV P-P Max

C. -12V ,±3%; 0.1A to 0.3A load

Ripple voltage: 100mV P-P Max

1. Input Voltage

95VAC to 130VA

(50 Hz/60Hz)

3750V

40kHz

70%

2. Line Isolation

3. Switching Frequency

4. Efficiency @ Full Load

Slope Compensation

A fraction of the oscillator ramp can be resistively

summed with the current sense signal to provide slope

compensation for converters requiring duty cycles over

50%.

Note that capacitor, C, forms a filter with R2 to suppress

the leading edge switch spikes.

UNITRODE INTEGRATED CIRCUITS

7 CONTINENTAL BLVD. • MERRIMACK, NH 03054

TEL. (603) 424-2410 • FAX (603)424-3460

IMPORTANT NOTICE

Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue

any product or service without notice, and advise customers to obtain the latest version of relevant information

to verify, before placing orders, that information being relied on is current and complete. All products are sold

subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those

pertaining to warranty, patent infringement, and limitation of liability.

TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in

accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent

TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily

performed, except those mandated by government requirements.

CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF

DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL

APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR

WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER

CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO

BE FULLY AT THE CUSTOMER’S RISK.

In order to minimize risks associated with the customer’s applications, adequate design and operating

safeguards must be provided by the customer to minimize inherent or procedural hazards.

TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent

that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other

intellectual property right of TI covering or relating to any combination, machine, or process in which such

semiconductor products or services might be or are used. TI’s publication of information regarding any third

party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.

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UC2845AD8TR产品参数

型号:	UC2845AD8TR
是否无铅：	含铅
是否Rohs认证：	符合
生命周期：	Active
IHS 制造商：	ROCHESTER ELECTRONICS LLC
零件包装代码：	SOIC
包装说明：	GREEN, PLASTIC, SOIC-8
针数：	8
Reach Compliance Code：	unknown
风险等级：	5.08
Is Samacsys：	N
模拟集成电路 - 其他类型：	SWITCHING CONTROLLER
控制模式：	CURRENT-MODE
控制技术：	PULSE WIDTH MODULATION
最大输入电压：	25 V
最小输入电压：	8.2 V
标称输入电压：	15 V
JESD-30 代码：	R-PDSO-G8
JESD-609代码：	e4
长度：	4.9 mm
湿度敏感等级：	1
功能数量：	1
端子数量：	8
最高工作温度：	85 °C
最低工作温度：	-40 °C
最大输出电流：	1 A
封装主体材料：	PLASTIC/EPOXY
封装代码：	SOP
封装形状：	RECTANGULAR
封装形式：	SMALL OUTLINE
峰值回流温度（摄氏度）：	260
座面最大高度：	1.75 mm
表面贴装：	YES
切换器配置：	SINGLE
最大切换频率：	500 kHz
温度等级：	INDUSTRIAL
端子面层：	NICKEL PALLADIUM GOLD
端子形式：	GULL WING
端子节距：	1.27 mm
端子位置：	DUAL
处于峰值回流温度下的最长时间：	NOT SPECIFIED
宽度：	3.9 mm
Base Number Matches：	1

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