CS2841B Datasheet by ON Semiconductor

Paragu— ======= o O ﬁééi zzzzzzz 0N Semicmm‘luutor"a W «

© Semiconductor Components Industries, LLC, 2008

March, 2008 - Rev. 8

1Publication Order Number:

CS2841B/D

CS2841B

Automotive Current Mode

PWM Control Circuit

The CS2841B provides all the necessary features to implement

off-line fixed frequency current-mode control with a minimum

number of external components.

The CS2841B (a variation of the CS2843A) is designed specifically

for use in automotive operation. The low start threshold voltage of 8.0 V

(typ), and the ability to survive 40 V automotive load dump transients

are important for automotive subsystem designs. The CS2841 series

has a history of quality and reliability in automotive applications.

The CS2841B incorporates a precision temperature-controlled

oscillator with an internally trimmed discharge current to minimize

variations in frequency. Duty-cycles greater than 50% are also

possible. On board logic ensures that VREF is stabilized before the

output stage is enabled. Ion implant resistors provide tighter control of

undervoltage lockout.

Features

•Optimized for Off-Line Control

•Internally Trimmed Temperature Compensated Oscillator

•Maximum Duty-Cycle Clamp

•VREF Stabilized Before Output Stage Enabled

•Low Start-Up Current

•Pulse-By-Pulse Current Limiting

•Improved Undervoltage Lockout

•Double Pulse Suppression

•1.0 % Trimmed Bandgap Reference

•High Current Totem Pole Output

•Pb-Free Packages are Available*

*For additional information on our Pb-Free strategy and soldering details, please

download the ON Semiconductor Soldering and Mounting Techniques

Reference Manual, SOLDERRM/D.

CS2841B = Device Code

A = Assembly Location

WL = Wafer Lot

YY, Y = Year

WW = Work Week

G = Pb-Free Package

PDIP-8

N SUFFIX

CASE 626

PIN CONNECTIONS AND

MARKING DIAGRAM

VREF

VCC

VOUT

GND

COMP

VFB

Sense

OSC

SOIC-14

D SUFFIX

CASE 751A

GND

OSC

PWR GND

VOUT

Sense

VCC PWR

VCC

VFB

VREF

COMP

SOIC-14

PDIP-8

http://onsemi.com

CS2841BEB

AWL

YYWWG

CS2841BD14G

AWLYWW

See detailed ordering and shipping information in the package

dimensions section on page 2 of this data sheet.

ORDERING INFORMATION

Error Amphher

CS2841B

http://onsemi.com

Figure 1. Block Diagram

Oscillator

Set/

Reset

Undervoltage

Lockout Circuit

8.0 V/7.4 V

2.5 V

5.0 V

Reference

Internal

Bias

Output

Enable

Error

Amplifier

2 R

R1.0 V

Current

Sensing

Comparator

PWM

Latch

NOR

VCC

GND

OSC

VFB

COMP

Sense

VCC Pwr

VREF

VOUT

Pwr GND

MAXIMUM RATINGS

Rating Value Unit

Supply Voltage (Low Impedance Source) 40 V

Output Current ±1.0 A

Output Energy (Capacitive Load) 5.0 mJ

Analog Inputs (VFB, Sense) -0.3 to 5.5 V

Error Amp Output Sink Current 10 mA

Lead Temperature Soldering Wave Solder (through hole styles only) Note 1

Reflow (SMD styles only) Note 2

260 peak

230 peak

°C

Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the

Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect

device reliability.

1. 10 seconds max

2. 60 seconds max above 183°C

ORDERING INFORMATION

Device Package Shipping†

CS2841BEBN8 PDIP-8 50 Units / Rail

CS2841BEBN8G PDIP-8

(Pb-Free)

50 Units / Rail

CS2841BED14 SOIC-14 55 Units / Rail

CS2841BED14G SOIC-14

(Pb-Free)

55 Units / Rail

CS2841BEDR14 SOIC-14 2500 / Tape & Reel

CS2841BEDR14G SOIC-14

(Pb-Free)

2500 / Tape & Reel

†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging

Specifications Brochure, BRD8011/D.

AVCOMP

CS2841B

http://onsemi.com

ELECTRICAL CHARACTERISTICS (-40°C ≤ TA ≤ 85°C, RT = 680 kW, CT = 0.022 mF for Triangular Mode, VCC = 15 V (Note 3),

RT = 10 kW, CT = 3.3 nF for Sawtooth Mode (see Figure 7); unless otherwise specified.)

Characteristic Test Conditions Min Typ Max Unit

Reference Section

Output Voltage TJ = 25°C, IOUT = 1.0 mA 4.9 5.0 5.1 V

Line Regulation 8.4 ≤ VCC ≤ 16 V - 6.0 20 mV

Load Regulation 1.0 ≤ IOUT ≤ 20 mA - 6.0 25 mV

Temperature Stability Note 4 - 0.2 0.4 mV/°C

Total Output Variation Line, Load, Temp. Note 4 4.82 - 5.18 V

Output Noise Voltage 10 Hz ≤ f ≤ 10 kHz, TJ = 25°C. Note 4 - 50 - mV

Long Term Stability TA = 125°C, 1000 Hrs. Note 4 - 5.0 25 mV

Output Short Circuit TA = 25°C -30 -100 -180 mA

Oscillator Section

Initial Accuracy Sawtooth Mode: TJ = 25°C. See Figure 7.

Sawtooth Mode: -40°C ≤ TA ≤ +85°C

Triangular Mode: TJ =25°C. See Figure 7.

kHz

Voltage Stability 8.4 ≤ VCC ≤ 16 V - 0.2 1.0 %

Temperature Stability Sawtooth Mode: TMIN ≤ TA ≤ TMAX. Note 4

Triangular Mode: TMIN ≤ TA ≤ TMAX. Note 4

5.0

8.0

Amplitude VOSC (Peak to Peak) - 1.7 - V

Discharge Current TJ = 25°C

TMIN ≤ TA ≤ TMAX

7.4

7.2

8.3

9.2

9.4

Error Amp Section

Input Voltage VCOMP = 2.5 V 2.42 2.5 2.58 V

Input Bias Current VFB = 0 V - -0.3 -2.0 mA

AVOL 2.0 ≤ VOUT ≤ 4.0 V 65 90 - dB

Unity Gain Bandwidth Note 4 0.7 1.0 - MHz

PSRR 8.4 V ≤ VCC ≤ 16 V 60 70 - dB

Output Sink Current VFB = 2.7 V, VCOMP = 1.1 V 2.0 6.0 - mA

Output Source Current VFB = 2.3 V, VCOMP = 5.0 V -0.5 -0.8 - mA

VOUT High VFB = 2.3 V, RL = 15 kW to Ground 5.0 6.0 - V

VOUT Low VFB = 2.7 V, RL = 15 kW to VREF - 0.7 1.1 V

Current Sense Section

Gain Notes 5 and 6 2.85 3.0 3.15 V/V

Maximum Input Signal VCOMP = 5.0 V. Note 5 0.9 1.0 1.1 V

PSRR 12 V ≤ VCC ≤ 25 V. Note 5 - 70 - dB

Input Bias Current VSense = 0 V - -2.0 -10 mA

Delay to Output TJ = 25°C. Note 4 - 150 300 ns

3. Adjust VCC above the start threshold before setting at 15 V

4. These parameters, although guaranteed, are not 100% tested in production

5. Parameter measured at trip point of latch with VFB = 0

6. Gain defined as:

A+DVCOMP

DVSense ; 0 vVSense v0.8V.

CS2841B

http://onsemi.com

ELECTRICAL CHARACTERISTICS (-40°C ≤ TA ≤ 85°C, RT = 680 kW, CT = 0.022 mF for Triangular Mode, VCC = 15 V (Note 3),

RT = 10 kW, CT = 3.3 nF for Sawtooth Mode (see Figure 7); unless otherwise specified.)

Characteristic UnitMaxTypMinTest Conditions

Output Section

Output Low Level ISINK = 20 mA

ISINK = 200 mA

0.1

1.5

0.4

2.2

Output High Level ISOURCE = 20 mA

ISOURCE = 200 mA

13.5

Rise Time TJ = 25°C, CL = 1.0 nF. Note 7 - 50 150 ns

Fall Time TJ = 25°C, CL = 1.0 nF. Note 7 - 50 150 ns

Output Leakage Undervoltage Active, VOUT = 0 - -0.01 -10 mA

Total Standby Current

Startup Current - - 0.5 1.0 mA

Operating Supply Current ICC VFB = VSense = 0 V, RT = 10 kW, CT = 3.3 nF -11 17 mA

Undervoltage Lockout Section

Start Threshold - 7.6 8.0 8.4 V

Min. Operating Voltage After Turn On 7.0 7.4 7.8 V

7. These parameters, although guaranteed, are not 100% tested in production.

PACKAGE PIN DESCRIPTION

PACKAGE PIN #

PIN SYMBOL FUNCTION

PDIP-8 SOIC-14

1 1 COMP Error Amp Output, Used to Compensate Error Amplifier

2 3 VFB Error Amp Inverting Input

3 5 Sense Noninverting Input to Current Sense Comparator

4 7 OSC Oscillator Timing Network with Capacitor to Ground, Resistor to VREF

5 8 GND Ground

9Pwr GND Output Driver Ground

6 10 VOUT Output Drive Pin

11 VCC Pwr Output Driver Positive Supply

7 12 VCC Positive Power Supply

8 14 VREF Output of 5.0 V Internal Reference

2, 4, 6, 13 NC No Connection

RT : 680 :2 RT: 15 ks: % O 4‘ x ErrorAmp VFE Vcc Adlus‘ 5525415 5 0 k£2 Sense Sense vOUT 4.7 m Adwst ? osc GND H 0 CT ___ Figure 4. Test Circuit hltp://onsemi.com 5

CS2841B

http://onsemi.com

TYPICAL PERFORMANCE CHARACTERISTICS

Figure 2. Oscillator Frequency vs. CTFigure 3. Oscillator Duty Cycle vs. RT

900

800

700

600

500

Frequency (kHz)

.0005 .001 .002 .04 .05

CT (mF)

400

300

200

100

.03.02.01.003 .005

RT = 680 W

RT = 1.5 kW

RT = 10 kW

100

Duty Cycle (%)

RT (W)

100

200

300

400

500

700

1 k

2 k

3 k

4 k

5 k

7 k

10 k

Figure 4. Test Circuit

VREF

VCC

VOUT

GND

COMP

VFB

Sense

OSC

CS2841B

4.7 kW

1.0 kW

Error Amp

Adjust

2N2222

100 kW

5.0 kW

Sense

Adjust

0.1 mF

0.1 mF1.0 kW

1.0 W

VREF

VCC

VOUT

GND

<15ma>

CS2841B

http://onsemi.com

CIRCUIT DESCRIPTION

Undervoltage Lockout

During Undervoltage Lockout (Figure 5), the output

driver is biased to a high impedance state. The output should

be shunted to ground with a resistor to prevent output

leakage current from activating the power switch.

Figure 5. Typical Undervoltage Characteristics

ON/OFF Command

to Reset of IC

VCC

VON = 8.0 V

VOFF = 7.4 V

VCC

ICC

7.4 V 8.0 V

< 15 mA

< 1.0 mA

PWM Waveform

To generate the PWM waveform, the control voltage from

the error amplifier is compared to a current sense signal

representing the peak output inductor current (Figure 6). An

increase in VCC causes the inductor current slope to

increase, thus reducing the duty cycle. This is an inherent

feed-forward characteristic of current mode control, since

the control voltage does not have to change during changes

of input supply voltage.

Figure 6. Timing Diagram for Key CS2841B

Parameters

Switch

Current

EA Output

VCC

OSC

RESET

OSC

When the power supply sees a sudden large output current

increase, the control voltage will increase allowing the duty

cycle to momentarily increase. Since the duty cycle tends to

exceed the maximum allowed to prevent transformer

saturation in some power supplies, the internal oscillator

waveform provides the maximum duty cycle clamp as

programmed by the selection of OSC components.

Figure 7. Oscillator Timing Network and

Parameters

Internal Clock

Triangular Mode

VOSC

Internal Clock

Small RT (≈ 700 kW)

Large RT (≈ 10 kW)

Sawtooth Mode

Timing Parameters

Vupper

Vlower

tctd

VREF

OSC

GND

Setting the Oscillator

Oscillator timing capacitor, CT, is charged by VREF

through RT and discharged by an internal current source.

During the discharge time, the internal clock signal blanks

out the output to the Low state, thus providing a user selected

maximum duty cycle clamp. Charge and discharge times are

determined by the general formulas:

IOHF Cm 0,1 HF]: hltp://onsemi.com 7

CS2841B

http://onsemi.com

tc+RTCTlnǒVREF *Vlower

VREF *VupperǓ

td+RTCTlnǒVREF *IdRT*Vupper

VREF *IdRT*VlowerǓ

Substituting in typical values for the parameters in the

above formulas:

VREF +5.0V

Vupper +2.7V

Vlower +1.0V

Id+8.3mA

tc[0.5534RTCT

td+RTCTlnǒ2.3 *0.0083RT

4.0 *0.0083RTǓ

The frequency and maximum duty cycle can be

determined from the Typical Performance Characteristic

graphs.

Grounding

High peak currents associated with capacitive loads

necessitate careful grounding techniques. Timing and

bypass capacitors should be connected close to GND pin in

a single point ground.

The transistor and 5.0 kW potentiometer are used to

sample the oscillator waveform and apply an adjustable

ramp to Sense.

C10

0.1 mF

10 mF0.1 mF

C13

4.7 nF

OSC

VREF

VCC PVCC

VOUT

SENSE

COMP

VFB

GND PGND

4.99 k

1.0 %

C14

47 pF

22.1 k

C11

0.33 mF

1.0 k

C12

10 nF

4.99 k

1.0 %

MTDISN06VTL4

0.2

1.0 %

VPR

GND

2n4401

DZ1

13 V

1N5243B

4.7 k

68 mF68 mF

4.7 pF

100 V

MURS120T3

VCC

VCC-GND

0.1 mF

1000 mF

0.1 mF

D2 MBR360 L1 2.2 mH

VCC = 5.0 V @ 750 mA

2.0 k

CS2841B

20T

Figure 8. Flyback Application

OSC 0 CC R3 (IE: MTP12NIO VouT 10 R5 SENSE woo COMP _]_C7 R6 R7 10k in 1Nsaia InputVoka Output Voltag Figure 9. Boos! Application hitp://onsemi.com a

CS2841B

http://onsemi.com

Figure 9. Boost Application

0.1 mF

10 mF0.1 mF

470 pF

OSC

VREF

VCC

VOUT

SENSE

COMP

GND

2.0 k C8

1.0 nF

100

MTP12N10

1.0

VPR

GND

1N5818

100 V

17 V

D1 1N5818

100 mH

Input Voltage Range: 8.0 V to 16 V

Output Voltage: 17 V @ 100 mA > 300 mA

3.0 k

CS2841B

0.01 mF

10 k

100 mF

12 k

C2 0.1 mF

330 mF

PACKAGE THERMAL DATA

Parameter PDIP-8 SOIC-14 Unit

RqJC Typical 52 30 °C/W

RqJA Typical 100 125 °C/W

um: 2 IMIEE

CS2841B

http://onsemi.com

PACKAGE DIMENSIONS

PDIP-8

CASE 626-05

ISSUE L

NOTES:

1. DIMENSION L TO CENTER OF LEAD WHEN

FORMED PARALLEL.

2. PACKAGE CONTOUR OPTIONAL (ROUND OR

SQUARE CORNERS).

3. DIMENSIONING AND TOLERANCING PER ANSI

Y14.5M, 1982.

NOTE 2 -A-

-B-

-T-

SEATING

PLANE

0.13 (0.005) B M

DIM MIN MAX MIN MAX

INCHESMILLIMETERS

A9.40 10.16 0.370 0.400

B6.10 6.60 0.240 0.260

C3.94 4.45 0.155 0.175

D0.38 0.51 0.015 0.020

F1.02 1.78 0.040 0.070

G2.54 BSC 0.100 BSC

H0.76 1.27 0.030 0.050

J0.20 0.30 0.008 0.012

K2.92 3.43 0.115 0.135

L7.62 BSC 0.300 BSC

M--- 10 --- 10

N0.76 1.01 0.030 0.040

1—1 2 conOLLINs DIMENSION MILLIMEIER HiFIiHiHiHiHiH a DIMENSIONSAANDBDO NOTINCLUDE MOLD PROTRUSION o MAXIMUM MOLD PROTRUSIDN u 15 In DOS) FER SIDE 5 DIMENSION D DoES NOT INCLUDE DAMBAR FRDTRUSION ALLOWABLE DIMENSION AI MAXIMuM MAIERIAL coNDIIIoN O DAMBAR FROTRuSIoN SHALL BE D I27 In ousI mIAL IN EXCESS oE THE D LI‘LI‘LLLHLIIi Sermccmiuctnv m J

CS2841B

http://onsemi.com

PACKAGE DIMENSIONS

SOIC-14

CASE 751A-03

ISSUE J

NOTES:

1. DIMENSIONING AND TOLERANCING PER

ANSI Y14.5M, 1982.

2. CONTROLLING DIMENSION: MILLIMETER.

3. DIMENSIONS A AND B DO NOT INCLUDE

MOLD PROTRUSION.

4. MAXIMUM MOLD PROTRUSION 0.15 (0.006)

PER SIDE.

5. DIMENSION D DOES NOT INCLUDE

DAMBAR PROTRUSION. ALLOWABLE

DAMBAR PROTRUSION SHALL BE 0.127

(0.005) TOTAL IN EXCESS OF THE D

DIMENSION AT MAXIMUM MATERIAL

CONDITION.

-A-

-B-

P7 PL

14 8

0.25 (0.010) B M

0.25 (0.010) A S

-T-

RX 45

SEATING

PLANE D14 PL K

_DIM MIN MAX MIN MAX

INCHESMILLIMETERS

A8.55 8.75 0.337 0.344

B3.80 4.00 0.150 0.157

C1.35 1.75 0.054 0.068

D0.35 0.49 0.014 0.019

F0.40 1.25 0.016 0.049

G1.27 BSC 0.050 BSC

J0.19 0.25 0.008 0.009

K0.10 0.25 0.004 0.009

M0 7 0 7

P5.80 6.20 0.228 0.244

R0.25 0.50 0.010 0.019

__ __

7.04

14X

0.58

14X

1.52

1.27

DIMENSIONS: MILLIMETERS

PITCH

SOLDERING FOOTPRINT

ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice

to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability

arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.

“Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All

operating parameters, including “Typicals” must be validated for each customer application by customer's technical experts. SCILLC does not convey any license under its patent rights

nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications

intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should

Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates,

and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death

associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal

Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.

CS2841B/D

PUBLICATION ORDERING INFORMATION

N. American Technical Support: 800-282-9855 Toll Free

USA/Canada

Europe, Middle East and Africa Technical Support:

Phone: 421 33 790 2910

Japan Customer Focus Center

Phone: 81-3-5773-3850

LITERATURE FULFILLMENT:

Literature Distribution Center for ON Semiconductor

P.O. Box 5163, Denver, Colorado 80217 USA