AP3845S8LA [ANACHIP]

High Performance Current Mode PWM Controller; 高性能电流模式PWM控制器


型号：	AP3845S8LA
厂家：	ANACHIP CORP
描述：	High Performance Current Mode PWM Controller 高性能电流模式PWM控制器稳压器开关式稳压器或控制器电源电路开关式控制器光电二极管
文件：	总8页 (文件大小：216K)
中文：	中文翻译
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AP3842/3/4/5

High Performance Current Mode PWM Controller

Features

General Description

• Optimized for Off-Line and DC to DC Converters

• Low Start-Up Current (≦0.5mA)

The AP3842/3/4/5 family of control ICs provides the

necessary features to implement off-line or DC to

DC fixed frequency current mode control schemes

with a minimal external parts count. Internally

implemented circuits include under voltage lockout

featuring start-up current less than 0.5 mA, a

precision reference trimmed for accuracy at the

error amp input, logic to insure latched operation, a

PWM comparator which also provides current limit

control, and a totem pole output stage designed to

source or sink high peak current. The output stage,

suitable for driving N-Channel MOSFETs, is low in

the off-state.

• Automatic Feed Forward Compensation

• Pulse-by-Pulse Current Limiting

• Enhanced Load Response Characteristics

• Under-Voltage Lockout (UVLO) with Hysteresis

• Double Pulse Suppression

• High Current Totem Pole Output

• Internally Trimmed Bandgap Reference

• Current Mode Operation to 500KHZ

• Low Ro Error Amplifier

Pin Connections

PDIP-8L, SOP-8L

Top View

Differences between members of this family are the

under-voltage lockout thresholds and maximum

duty cycle ranges. The AP3842 and AP3844 have

UVLO thresholds of 16V(on) and 10V(off), ideally

suited for off-line applications. The corresponding

thresholds for the AP3843 and AP3845 are 8.5V

and 7.6V. The AP3842 and AP3843 can operate to

duty cycles approaching 100%. A range of the zero

to < 50% is obtained by the AP3844 and AP3845

by the addition of an internal toggle flip flop which

blanks the output off every other clock cycle.

COMP.

V_FB

V_REF

V_I

I_SENSE

R_T/C_T

OUTPUT

GROUND

Ordering Information

AP 384X X X X

Part No.

Package

Packing

Lead Free

2:3842

3:3843

4:3844

5:3845

S8:SOP-8L

N8:PDIP-8L

Blank : Normal

Blank: Tube

L : Lead Free Package

A : Taping

This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of

this product. No rights under any patent accompany the sale of the product.

Rev.1.0 Oct.11, 2004

1/8

AP3842/3/4/5

High Performance Current Mode PWM Controller

Block Diagram ( toggle flip flop used only in AP3844 and AP3845 )

36V

UVLO

VREF

16V

5V 50mA

S/R

REF

GROUND

RT/CT

INTERNAL

BIAS

2.50V

VREF GOOD

LOGIC

OUTPUT

OSC.

ERROR AMP.

VFB

PWM

LATCH

CURRENT

SENSE

COMP

CURRENT

SENSE

AP384X

COMPARATOR

Absolute Maximum Ratings

Symbol

Parameter

Value

Unit

V_i

I_o

Supply Voltage (low impedance source)

Self Limiting

±0.7

Supply Voltage (li < 30mA)

Output Current

µJ

E_o

Output Energy (capacitive load)

Analog Inputs (pins2,3)

-0.3 to 5.5

Error Amplifier Output Sink Current

Power Dissipation at T_amb≦50⁰C (PDIP8)

Power Dissipation at T_amb≦25⁰C (SOP8)

Storage Temperature Range

P_tot

T_stg

T_L

1.25

800

^oC

-65 to 150

260

Lead Temperature (soldering 10s)

*Notes: 1. All voltages are with respect to pin 5, all currents are positive into the specified terminal.

Electrical Characteristics

(Unless otherwise stated, these specifications apply for 0≦T_amb≦70^oC for AP384X ; V_i= 15V(note 5); R_T= 10KΩ;C_T= 3.3nF)

AP384X

Symbol

Parameter

Test Conditions

Unit

Min. Typ. Max.

REFERENCE SECTION

V_REF

∆V_REF

Output Voltage

Tj = 25⁰C I₀=1mA

12V≦V_i≦25V

4.90 5.00 5.10

Line Regulation

Load Regulation

∆V_REF

1mA≦I_o≦20mA

∆V_REF/∆T

Temperature Stability

Total Output Variation

(Notes 2)

0.2 0.4 mV/⁰C

Line, Load, Temperature (Notes 2) 4.82

10Hz≦f≦10KHz Tj=25⁰C (Notes

5.18

e_N

Output Noise Voltage

µV

Long Term Stability

Output Short Circuit current

T_amb=125⁰C, 1000Hrs (Notes 2)

I_SC

-85 -120 mA

Anachip Corp.

www.anachip.com.tw

Rev.1.0 Oct.11, 2004

2/8

AP3842/3/4/5

High Performance Current Mode PWM Controller

Electrical Characteristics(Continued)

(Unless otherwise stated, these specifications apply for 0≦T_amb≦70^oC for AP384X ; V_i= 15V(note 5); R_T= 10KΩ;C_T= 3.3nF)

AP384X

Symbol

Parameter

Test Conditions

Unit

Min. Typ. Max.

OSCILLATOR SECTION

f_s

Oscillator Frequency

Tj=25⁰C (Notes 6, 7)

12V≦V_i≦25V

_MIN≦T_amb≦T_MAX(Notes 2)

V_PIN4Peak to Peak

Tj=25⁰C V_PIN4=2V

0.2

0.5

1.6

KHz

Voltage Stability

Temperature Stability

Amplitude

V₄

Discharge Current

7.8 8.3 8.8

ERROR AMP SECTION

V₂

I_b

Feedback Input Voltage

V_PIN1=2.5V

V_FB=5V

2.42 2.50 2.58

µA

Input Bias Current

A_VOL

-0.1

-2

0V≦V₀≦4V

0.7

Unity Gain Bandwidth

Supply Voltage Rejection

Ratio

Tj=25^oC

MHz

SVRR

12V≦V_i≦25V

I_O

Output Sink Current

Output Source Current

V_OUTHigh

V_PIN2=2.7V V_PIN1=1.1V

V_PIN2=2.3V V_PIN1=5V

V_PIN2=2.3V; R_L=15KΩ to ground

V_PIN2=2.7V; R_L=15KΩ to pin 8

-0.5 -0.8

V_OUTLow

0.8 1.1

CURRENT SENSE SECTION

G_v

V₃

Gain

(Notes3&Notes4)

V_PIN1=5V (Notes3)

2.85

0.9

3.15 V/V

Maximum Input Signal

Supply Voltage Rejection

Ratio

1.1

SVRR

I_b

12≦V_i≦25V (Notes3)

-2

Input Bias Current

Delay to Output

-10

µA

150 300

OUTPUT SECTION

I_SINK= 20mA

I_SINK= 200mA

0.1 0.4

1.6 2.2

V_OL

Output Low Level

I_SOURCE= 20mA

13 13.5

12 13.5

V_OH

Output High Level

I_SOURCE= 200mA

T_r

T_f

V_OLS

Rise Time

Fall Time

UVLO Saturation

Tj=25⁰C C_L=1nF (Notes2)

Vcc = 6V ; Isink = 1mA

50 150

0.1 1.1

UNDER-VOLTAGE LOCKOUT SECTION

3842/4

3843/5

3842/4

3843/5

14.5 16 17.5

Start Threshold

7.8 8.4

Min Operating Voltage After

Turn-on

8.5

10 11.5

7.0 7.6 8.2

PWM SECTION

3842/3

3844/5

Maximum Duty Cycle

Minimum Duty Cycle

TOTAL STANDBY CURRENT

Vi=14V,3842/4 ;

Vi=6.5V 3843/5

V_PIN2=V_PIN3=0V

I_i=25mA

I_st

Start-up Current

0.3 0.5

I_i

V_iz

Operating Supply Current

Zener Voltage

Anachip Corp.

www.anachip.com.tw

Rev.1.0 Oct.11, 2004

3/8

AP3842/3/4/5

High Performance Current Mode PWM Controller

Notes：2.These parameters, although guaranteed, are not 100% tested in production.

3.Parameter measured at trip point of latch with V_PIN2=0.

4.Gain defined as:

∆V_PIN1

; 0≦V_PIN3≦0.8V

∆V_PIN3

5.Adjust V_iabove the start threshold before setting at 15V.

6.Output frequency equals oscillator frequency for the AP3842 and AP3843.

7.Output frequency is one and half oscillator frequency for the AP3844 and AP3845.

Figure 1 : Error Amp Configuration.

2.5V

0.8 mA

V_FB

COMP

Error amp can source or sink up to 0.5mA

Figure 2 : Under Voltage Lockout.

ON/OFF COMMAND

TO REST OF IC

AP3842 AP3843

<17 mA

<1 mA

AP3844 AP3845

16V

10V

8.4V

7.6V

OFF

OFF ON

During Under-Voltage Lockout, the output driver is biased to sink minor amounts of current. Pin 6 should be

shunted to ground with a bleeder resistor to prevent activating the power switch with extraneous leakage

currents.

Figure 3 : Current Sense Circuit.

ERROR

AMP

COMP

CURRENT

SENSE

COMPARATOR

CURRENT

SENSE

GND

Anachip Corp.

www.anachip.com.tw

Rev.1.0 Oct.11, 2004

4/8

AP3842/3/4/5

High Performance Current Mode PWM Controller

Peak current(i_s) is determined by the formula

1.0V

I_Smax ≈

R_S

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

Figure 4.

V_REF

R_T

R_T/C_T

C_T

GROUND

1.72

R_TC_T

for R_T> 5KΩ f=

Figure 5 : Open Loop Test Circuit.

REF

4.7K

2N2222

COMP.

REF

100K

0.1

ERROR AMP.

ADJUST

0.1

AP3842

SENSE

ADJUST

OUTPUT

GROUND

OUTPUT

SENSE

4.7K

GROUND

High peak currents associated with capacitive loads necessitate careful grounding techniques. Timing and

bypass apacitors should be connected close to pin 5 in a single point ground. The transistor and 5 KΩ

potentiometer are used to sample the oscillator waveform and apply an adjustable ramp to pin 3.

Figure 6 : Shutdown Techniques.

REF

COMP

330K

SENSE

500K

SHUTDOWN

TO CURRENT

SENSE RESISTOR

Anachip Corp.

www.anachip.com.tw

Rev.1.0 Oct.11, 2004

5/8

AP3842/3/4/5

High Performance Current Mode PWM Controller

Shutdown of the AP3842 can be accomplished in two ways; either raise pin 3 above 1V or pull pin 1 below a

voltage two diode drops above ground. Either one of them causes the output of the PWM comparator to be

high (refer to block diagram). The PWM latch is reset dominant so that the output will remain low until the

next clock cycle after the shutdown condition at pins 1 and/or 3 is removed. In one example, an externally

latched shutdown may be accomplished by adding an SCR that will be reset by cycling V_ibelow the lower

UVLO threshold. At this point the reference turns off, allowing the SCR to reset.

Figure 7 : Slope Compensation.

Uref

0.1uF

RT/CT

Isense

AP3842/3

Rsense

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 R₂to

suppress the leading edge switch spikes.

Anachip Corp.

www.anachip.com.tw

Rev.1.0 Oct.11, 2004

6/8

AP3842/3/4/5

High Performance Current Mode PWM Controller

Package Diagrams

(1) PDIP-8L (Plastic Dual-in-line Package)

E-PIN O0.118 inch

(4X)

PIN #1 INDENT O0.025 DEEP 0.006-0.008 inch

(4X)

Dimensions in millimeters

Dimensions in inches

Symbol

Min.

Nom.

Max.

5.33

Min.

Nom.

Max.

0.210

0.38

3.1

0.015

0.122

0.014

0.055

0.032

0.008

0.355

0.300

0.242

3.30

0.46

1.52

0.99

0.25

9.27

7.94

6.35

2.54

3.3

3.5

0.130

0.018

0.060

0.039

0.010

0.365

0.313

0.250

0.100

0.130

0.350

0.033

0.138

0.022

0.065

0.045

0.014

0.375

0.325

0.258

0.36

1.4

0.56

1.65

1.14

0.36

9.53

8.26

6.55

0.81

0.20

9.02

7.62

6.15

2.92

8.38

0.71

3.81

9.40

0.97

0.115

0.330

0.028

0.150

0.370

0.038

8.89

0.84

Anachip Corp.

www.anachip.com.tw

Rev.1.0 Oct.11, 2004

7/8

AP3842/3/4/5

High Performance Current Mode PWM Controller

(2) SOP-8L (JEDEC Small Outline Package)

VIEW "A"

0.015x45

7 (4X)

VIEW "A"

Dimensions In Millimeters

Dimensions In Inches

Symbol

Min.

1.40

0.10

1.30

0.33

0.19

4.80

3.70

Nom.

1.60

Max.

1.75

0.25

1.50

0.51

0.25

5.30

4.10

6.20

1.27

0.10

8^O

Min.

Nom.

0.063

Max.

0.055

0.040

0.051

0.013

0.0075

0.189

0.146

0.069

0.100

0.059

0.020

0.010

0.209

0.161

0.244

0.050

0.004

8^O

1.45

0.41

0.20

5.05

3.90

1.27

5.99

0.71

0.057

0.016

0.008

0.199

0.154

0.050

0.236

0.028

5.79

0.38

0.228

0.015

0^O

Marking Information

Logo

2,3,4,5

Blank: normal

AP384XB

Part No.

L: Lead Free Package

YYWW X X

ID code: internal

Xth Week : 01~52

Year : "01"=2001

"02"=2002

Anachip Corp.

www.anachip.com.tw

Rev.1.0 Oct.11, 2004

8/8

AP3845S8LA [ANACHIP]

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