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 V
REF
is stabilized before the
output stage is enabled. Ion implant resistors provide tighter control of
undervoltage lockout.
Features
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8
1
PDIP-8
N SUFFIX
CASE 626
14
1
SOIC-14
D SUFFIX
CASE 751A
•
•
•
•
•
•
•
•
•
•
•
Optimized for Off-Line Control
Internally Trimmed Temperature Compensated Oscillator
Maximum Duty-Cycle Clamp
V
REF
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*
PIN CONNECTIONS AND
MARKING DIAGRAM
COMP
CS2841BEB
AWL
YYWWG
V
FB
Sense
OSC
V
REF
V
CC
V
OUT
GND
PDIP-8
14
1
CS2841BD14G
AWLYWW
SOIC-14
COMP
NC
V
FB
NC
Sense
NC
OSC
V
REF
NC
V
CC
V
CC
PWR
V
OUT
PWR GND
GND
CS2841B
A
WL
YY, Y
WW
G
= Device Code
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb-Free Package
*For additional information on our Pb-Free strategy and soldering details, please
download the ON Semiconductor Soldering and Mounting Techniques
Reference Manual, SOLDERRM/D.
©
Semiconductor Components Industries, LLC, 2008
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 2 of this data sheet.
1
March, 2008 - Rev. 8
Publication Order Number:
CS2841B/D
CS2841B
V
CC
V
CC
Pwr
Undervoltage
Lockout Circuit
Set/
Reset
8.0 V/7.4 V
2.5 V
Output
Enable
NOR
5.0 V
Reference
Internal
Bias
GND
V
REF
OSC
Oscillator
S
V
OUT
+
-
Error
Amplifier
2R
V
C
R
R
1.0 V
Current
Sensing
Comparator
PWM
Latch
Pwr GND
V
FB
COMP
Sense
Figure 1. Block Diagram
MAXIMUM RATINGS
Rating
Supply Voltage (Low Impedance Source)
Output Current
Output Energy (Capacitive Load)
Analog Inputs (V
FB
, Sense)
Error Amp Output Sink Current
Lead Temperature Soldering
Wave Solder (through hole styles only) Note 1
Reflow (SMD styles only) Note 2
Value
40
±1.0
5.0
-0.3 to 5.5
10
260 peak
230 peak
Unit
V
A
mJ
V
mA
°C
°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
CS2841BEBN8
CS2841BEBN8G
CS2841BED14
CS2841BED14G
CS2841BEDR14
CS2841BEDR14G
Package
PDIP-8
PDIP-8
(Pb-Free)
SOIC-14
SOIC-14
(Pb-Free)
SOIC-14
SOIC-14
(Pb-Free)
Shipping
†
50 Units / Rail
50 Units / Rail
55 Units / Rail
55 Units / Rail
2500 / Tape & Reel
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.
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2
CS2841B
ELECTRICAL CHARACTERISTICS
(-40°C
≤
T
A
≤
85°C, R
T
= 680 kW, C
T
= 0.022
mF
for Triangular Mode, V
CC
= 15 V (Note 3),
R
T
= 10 kW, C
T
= 3.3 nF for Sawtooth Mode (see Figure 7); unless otherwise specified.)
Characteristic
Reference Section
Output Voltage
Line Regulation
Load Regulation
Temperature Stability
Total Output Variation
Output Noise Voltage
Long Term Stability
Output Short Circuit
Oscillator Section
Initial Accuracy
Sawtooth Mode: T
J
= 25°C. See Figure 7.
Sawtooth Mode: -40°C
≤
T
A
≤
+85°C
Triangular Mode: T
J
=25°C. See Figure 7.
8.4
≤
V
CC
≤
16 V
Sawtooth Mode: T
MIN
≤
T
A
≤
T
MAX
. Note 4
Triangular Mode: T
MIN
≤
T
A
≤
T
MAX
. Note 4
V
OSC
(Peak to Peak)
T
J
= 25°C
T
MIN
≤
T
A
≤
T
MAX
47
44
44
-
-
-
-
7.4
7.2
52
52
52
0.2
5.0
8.0
1.7
8.3
-
57
60
60
1.0
-
-
-
9.2
9.4
kHz
kHz
kHz
%
%
%
V
mA
mA
T
J
= 25°C, I
OUT
= 1.0 mA
8.4
≤
V
CC
≤
16 V
1.0
≤
I
OUT
≤
20 mA
Note 4
Line, Load, Temp. Note 4
10 Hz
≤
f
≤
10 kHz, T
J
= 25°C. Note 4
T
A
= 125°C, 1000 Hrs. Note 4
T
A
= 25°C
4.9
-
-
-
4.82
-
-
-30
5.0
6.0
6.0
0.2
-
50
5.0
-100
5.1
20
25
0.4
5.18
-
25
-180
V
mV
mV
mV/°C
V
mV
mV
mA
Test Conditions
Min
Typ
Max
Unit
Voltage Stability
Temperature Stability
Amplitude
Discharge Current
Error Amp Section
Input Voltage
Input Bias Current
A
VOL
Unity Gain Bandwidth
PSRR
Output Sink Current
Output Source Current
V
OUT
High
V
OUT
Low
Current Sense Section
Gain
Maximum Input Signal
PSRR
Input Bias Current
Delay to Output
3.
4.
5.
6.
V
COMP
= 2.5 V
V
FB
= 0 V
2.0
≤
V
OUT
≤
4.0 V
Note 4
8.4 V
≤
V
CC
≤
16 V
V
FB
= 2.7 V, V
COMP
= 1.1 V
V
FB
= 2.3 V, V
COMP
= 5.0 V
V
FB
= 2.3 V, R
L
= 15 kW to Ground
V
FB
= 2.7 V, R
L
= 15 kW to V
REF
2.42
-
65
0.7
60
2.0
-0.5
5.0
-
2.5
-0.3
90
1.0
70
6.0
-0.8
6.0
0.7
2.58
-2.0
-
-
-
-
-
-
1.1
V
mA
dB
MHz
dB
mA
mA
V
V
Notes 5 and 6
V
COMP
= 5.0 V. Note 5
12 V
≤
V
CC
≤
25 V. Note 5
V
Sense
= 0 V
T
J
= 25°C. Note 4
2.85
0.9
-
-
-
3.0
1.0
70
-2.0
150
3.15
1.1
-
-10
300
V/V
V
dB
mA
ns
Adjust V
CC
above the start threshold before setting at 15 V
These parameters, although guaranteed, are not 100% tested in production
Parameter measured at trip point of latch with V
FB
= 0
Gain defined as:
A
+
DV
COMP
; 0
v
VSense
v
0.8 V.
DV
Sense
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3
CS2841B
ELECTRICAL CHARACTERISTICS
(-40°C
≤
T
A
≤
85°C, R
T
= 680 kW, C
T
= 0.022
mF
for Triangular Mode, V
CC
= 15 V (Note 3),
R
T
= 10 kW, C
T
= 3.3 nF for Sawtooth Mode (see Figure 7); unless otherwise specified.)
Characteristic
Output Section
Output Low Level
Output High Level
Rise Time
Fall Time
Output Leakage
Total Standby Current
Startup Current
Operating Supply Current I
CC
Undervoltage Lockout Section
Start Threshold
Min. Operating Voltage
After Turn On
-
7.6
7.0
8.0
7.4
8.4
7.8
V
V
-
V
FB
= V
Sense
= 0 V, R
T
= 10 kW, C
T
= 3.3 nF
-
-
0.5
11
1.0
17
mA
mA
I
SINK
= 20 mA
I
SINK
= 200 mA
I
SOURCE
= 20 mA
I
SOURCE
= 200 mA
T
J
= 25°C, C
L
= 1.0 nF. Note 7
T
J
= 25°C, C
L
= 1.0 nF. Note 7
Undervoltage Active, V
OUT
= 0
-
-
13
12
-
-
-
0.1
1.5
13.5
13.5
50
50
-0.01
0.4
2.2
-
-
150
150
-10
V
V
V
V
ns
ns
mA
Test Conditions
Min
Typ
Max
Unit
7. These parameters, although guaranteed, are not 100% tested in production.
PACKAGE PIN DESCRIPTION
PACKAGE PIN #
PDIP-8
1
2
3
4
5
SOIC-14
1
3
5
7
8
9
6
10
11
7
8
12
14
2, 4, 6, 13
PIN SYMBOL
COMP
V
FB
Sense
OSC
GND
Pwr GND
V
OUT
V
CC
Pwr
V
CC
V
REF
NC
FUNCTION
Error Amp Output, Used to Compensate Error Amplifier
Error Amp Inverting Input
Noninverting Input to Current Sense Comparator
Oscillator Timing Network with Capacitor to Ground, Resistor to V
REF
Ground
Output Driver Ground
Output Drive Pin
Output Driver Positive Supply
Positive Power Supply
Output of 5.0 V Internal Reference
No Connection
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4
CS2841B
TYPICAL PERFORMANCE CHARACTERISTICS
100
R
T
= 680
W
Duty Cycle (%)
.002 .003 .005
C
T
(mF)
.01
.02 .03 .04 .05
90
80
70
60
50
40
30
R
T
= 10 kW
20
10
100
200
300
400
500
700
10 k
1k
2k
3k
4k
5k
7k
V
CC
900
800
Frequency (kHz)
700
600
500
400
300
200
100
.0005
.001
R
T
= 1.5 kW
R
T
(W)
Figure 2. Oscillator Frequency vs. C
T
Figure 3. Oscillator Duty Cycle vs. R
T
V
REF
R
T
2N2222
4.7 kW
100 kW
COMP
1.0 kW
Error Amp
Adjust
5.0 kW
Sense
Adjust
V
REF
0.1
mF
V
FB
CS2841B
Sense
V
OUT
V
CC
0.1
mF
1.0 kW
1.0 W
V
OUT
A
4.7 kW
OSC
GND
GND
C
T
Figure 4. Test Circuit
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5
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