食品药品监督管理局简称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 u 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 ries 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
•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
•Pul−By−Pul Current Limiting
•Improved Undervoltage Lockout
ale•Double Pul 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, plea download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D.
CS2841B= Device Code
A= Asmbly 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
V REF
V CC
V OUT
GND
COMP
V FB
Sen
自考本科文凭
OSC
1
SOIC−14
D SUFFIX
美国之声广播电台CASE 751A
GND
OSC
PWR GND
NC
V OUT
Sen
V CC PWR
NC
V CC
V FB
NC
NC
V REF
COMP
1
SOIC−14
PDIP−8
<
CS2841BEBG
AWL
YYWW
See detailed ordering and shipping information in the package dimensions ction on page 2 of this data sheet.
ORDERING INFORMATION
Figure 1. Block Diagram
V CC
GND
OSC V FB
COMP Sen
V CC Pwr
V REF
V OUT
Pwr GND MAXIMUM RATINGS
Rating
Value Unit Supply Voltage (Low Impedance Source)40V Output Current
±1.0A Output Energy (Capacitive Load) 5.0m J Analog Inputs (V FB , Sen)−0.3 to 5.5
V Error Amp Output Sink Current 10mA Lead Temperature Soldering
Wave Solder (through hole styles only) Note 1Reflow (SMD styles only) Note 2
260 peak 230 peak
°C °C
Maximum ratings are tho values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit values (not normal operating conditions) and are not valid simultaneously. If the limits are exceeded, device functional operation is not implied,damage may occur and reliability may be affected.1.10 conds max
2.60 conds max above 183°C
ORDERING INFORMATION
Device
Package Shipping †CS2841BEBN8PDIP−850 Units / Rail CS2841BEBN8G PDIP−8(Pb−Free)50 Units / Rail CS2841BED14SOIC−1455 Units / Rail CS2841BED14G SOIC−14(Pb−Free)55 Units / Rail CS2841BEDR14SOIC−142500 / Tape & Reel CS2841BEDR14G
SOIC−14(Pb−Free)
ready
2500 / Tape & Reel
†For information on tape and reel specifications, including part orientation and tape sizes, plea refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D.
ELECTRICAL CHARACTERISTICS (−40°C ≤ T A≤ 85°C, R T = 680 k W, C T = 0.022 m F for Triangular Mode, V CC = 15 V (Note 3), R T = 10 k W, C T = 3.3 nF for Sawtooth Mode (e Figure 7); unless otherwi specified.)
Characteristic Test Conditions Min Typ Max Unit
Reference Section
Output Voltage T J = 25°C, I OUT = 1.0 mA 4.9 5.0 5.1V
Line Regulation8.4 ≤ V CC≤ 16 V− 6.020mV
Load Regulation 1.0 ≤ I OUT≤ 20 mA− 6.025mV
Temperature Stability Note 4−0.20.4mV/°C
Total Output Variation Line, Load, Temp. Note 4 4.82− 5.18V
Output Noi Voltage10 Hz ≤ f ≤ 10 kHz, T J = 25°C. Note 4−50−m V
Long Term Stability T A = 125°C, 1000 Hrs. Note 4− 5.025mV
Output Short Circuit T A = 25°C−30−100−180mA
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 7.47
44
44
52
52
52
57
60
60
kHz
kHz
kHz
Voltage Stability8.4 ≤ V CC≤ 16 V−0.2 1.0%
Temperature Stability Sawtooth Mode: T MIN≤ T A≤ T MAX. Note 4
Triangular Mode: T MIN≤ T A≤ T MAX. Note 4−
−
5.0
8.0
−
−
%
%
Amplitude V OSC (Peak to Peak)− 1.7−V
Discharge Current T J = 25°C
T MIN≤ T A≤ T MAX 7.4
7.2
8.3
−
9.2
9.4
mA
mA
Error Amp Section
Input Voltage V COMP = 2.5 V 2.42 2.5 2.58V Input Bias Current V FB = 0 V−−0.3−2.0m A A VOL 2.0 ≤ V OUT≤ 4.0 V6590−dB Unity Gain Bandwidth Note 40.7 1.0−MHz PSRR8.4 V ≤ V CC≤ 16 V6070−dB Output Sink Current V FB = 2.7 V, V COMP = 1.1 V 2.0 6.0−mA Output Source Current V FB = 2.3 V, V COMP = 5.0 V−0.5−0.8−mA V OUT High V FB = 2.3 V, R L = 15 k W to Ground 5.0 6.0−V V OUT Low V FB = 2.7 V, R L = 15 k W to V REF−0.7 1.1V Current Sen Section
Gain Notes 5 and 6 2.85 3.0 3.15V/V Maximum Input Signal V COMP = 5.0 V. Note 50.9 1.0 1.1V PSRR12 V ≤ V CC≤ 25 V. Note 5−70−dB Input Bias Current V Sen = 0 V−−2.0−10m A Delay to Output T J = 25°C. Note 4−150300ns
3.Adjust V CC above the start threshold before tting at 15 V
4.The parameters, although guaranteed, are not 100% tested in production
5.Parameter measured at trip point of latch with V FB = 0
6.Gain defined as:
A+D V COMP
prophecy
D V Sen;0v V Sen v0.8V.
ELECTRICAL CHARACTERISTICS (−40°C ≤ T A≤ 85°C, R T = 680 k W, C T = 0.022 m F for Triangular Mode, V CC = 15 V (Note 3), R T = 10 k W, C T = 3.3 nF for Sawtooth Mode (e Figure 7); unless otherwi specified.)
外语教育网
Characteristic Unit
Max
Typ
Min
口语交际练习题Test Conditions
Output Section
Output Low Level I SINK = 20 mA
I SINK = 200 mA −
−
0.1
1.5
0.4
2.2
V
V
Output High Level I SOURCE = 20 mA
I SOURCE = 200 mA 13
12
13.5
13.5
−
−
V
V
Ri Time T J = 25°C, C L = 1.0 nF. Note 7−50150ns Fall Time T J = 25°C, C L = 1.0 nF. Note 7−50150ns Output Leakage Undervoltage Active, V OUT = 0−−0.01−10m A Total Standby Current
Startup Current−−0.5 1.0mA Operating Supply Current I CC V FB = V Sen = 0 V, R T = 10 k W, C T = 3.3 nF−1117mA Undervoltage Lockout Section
Start Threshold−7.68.08.4V Min. Operating Voltage After Turn On7.07.47.8V 7.The parameters, although guaranteed, are not 100% tested in production.
PACKAGE PIN DESCRIPTION
PACKAGE PIN #
PIN SYMBOL FUNCTION
PDIP−8SOIC−14
11COMP Error Amp Output, Ud to Compensate Error Amplifier
23V FB Error Amp Inverting Input
35Sen Noninverting Input to Current Sen Comparator
47OSC Oscillator Timing Network with Capacitor to Ground, Resistor to V REF
58GND Ground
9Pwr GND Output Driver Ground
610V OUT Output Drive Pin
11V CC Pwr Output Driver Positive Supply
712V CC Positive Power Supply
814V REF Output of 5.0 V Internal Reference
2, 4, 6, 13NC No Connection
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 2. Oscillator Frequency vs. C T Figure 3. Oscillator Duty Cycle vs. R T
900800700600500F r e q u e n c y (k H z )
C T (m F)
400300200100R T (W )
100
200
300400500
700
1 k
2 k
3 k
4 k
5 k
7 k 10 k
Figure 4. Test Circuit
4.7 k 4.7 k 1.0 k V REF
V CC
V OUT
GND
CIRCUIT DESCRIPTION
Undervoltage Lockout
During Undervoltage Lockout (Figure 5), the output driver is biad 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
V CC
V CC
7.4 V
8.0 V
< 15 mA < 1.0 mA
喋血双雄小游戏PWM Waveform
To generate the PWM waveform, the control voltage from the error amplifier is compared to a current n signal reprenting the peak output inductor current (Figure 6). An increa in V CC caus the inductor current slope to increa, 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 V CC I O
V O
OSC RESET OSC When the power supply es a sudden large output current increa, the control
voltage will increa allowing the duty cycle to momentarily increa. 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 lection of OSC components.
Figure 7. Oscillator Timing Network and
Parameters
Timing Parameters
V REF
OSC
trouble maker什么意思GND
T
T
Setting the Oscillator
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 out the output to the Low state, thus providing a ur lected maximum duty cycle clamp. Charge and discharge times are determined by the general formulas:
