CS2841B Datasheet, PDF (1/6 Pages) Cherry Semiconductor Corporation – Automotive Current Mode PWM Control Circuit

CS2841B
Automotive Current Mode PWM
Control Circuit
Description
Features
The CS2841B provides all the nec-
essary features to implement off-
line fixed frequency current-mode
control with a minimum number of
external components.
The CS2841B (a variation of the
CS-2843A) is designed specifically
for use in automotive operation.
The low start threshold voltage of
8.0V (typ), and the ability to sur-
vive 40V automotive load dump
transients are important for auto-
motive subsystem designs. The
CS-2841 series has a history of
quality and reliability in automo-
tive applications.
The CS2841B incorporates a preci-
sion temperature-controlled oscil-
lator with an internally trimmed
discharge current to minimize vari-
ations 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 under-
voltage lockout.
Absolute Maximum Ratings
Supply Voltage (Low Impedance Source)...................................................40V
Output Current ...............................................................................................±1A
Output Energy (Capacitive Load) .................................................................5µJ
Analog Inputs (V_FB, Sense) ............................................................-0.3V to 5.5V
Error Amp Output Sink Current...............................................................10mA
Lead Temperature Soldering
Wave Solder (through hole styles only) ..........10 sec. max, 260°C peak
Reflow (SMD styles only) ...........60 sec. max above 183°C, 230°C peak
Block Diagram
s Optimized for Off-line
Control
s Internally Trimmed
Temperature
Compensated Oscillator
s Maximum Duty-cycle
Clamp
s V_REF Stabilized before
Output Stage Enabled
s Low Start-up Current
s Pulse-by-pulse Current
Limiting
s Improved Undervoltage
Lockout
s Double Pulse Suppression
s 1% Trimmed Bandgap
Reference
s High Current Totem Pole
Output
Package Options
8 Lead PDIP
V_CC
Gnd
OSC
V_FB
COMP
Sense
Undervoltage
Lock-out Circuit
8.0V/7.4V
Set/
5V
Reset Reference
2.50V
Oscillator
Output
Enable
Internal
Bias
NOR
+
–
Error
V_C
Amplifier
2R
R
S
R
1 V Current
Sensing
Comparator
PWM
Latch
V_CC Pwr
V_REF
V_OUT
Pwr Gnd
COMP 1
V_FB 2
Sense 3
OSC 4
8 V_REF
7 V_CC
6 V_OUT
5 Gnd
14 Lead SO Narrow
COMP 1
NC 2
V_FB 3
NC 4
Sense 5
NC 6
OSC 7
14 V_REF
13 NC
12 V_CC
11 V_CC Pwr
10 V_OUT
9 Pwr Gnd
8 Gnd
Rev. 6/23/99
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: [phone] Fax: [phone]
Email: [e-mail]
Web Site: www.cherry-semi.com
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