cs52845 ON Semiconductor, cs52845 Datasheet

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cs52845

Manufacturer Part Number
cs52845
Description
Current Mode Pwm Control Circuit
Manufacturer
ON Semiconductor
Datasheet
December, 2001 - Rev. 3
Supply Voltage (I
Supply Voltage (Low Impedance Source)...................................................30V
Output Current ...............................................................................................±1A
Output Energy (Capacitive Load) .................................................................5µJ
Analog Inputs (V
Error Amp Output Sink Current...............................................................10mA
Lead Temperature Soldering
COMP
The CS52845 provides all the nec-
essary features to implement off-
line fixed frequency current-mode
control with a minimum number
of external components.
The CS52845 incorporates a new
precision temperature-controlled
oscillator to minimize variations in
frequency. An internal toggle flip-
flop, which blanks the output
every other clock cycle, limits the
duty-cycle range to less than 50%.
Sense
OSC
Gnd
V
V
CC
FB
Current Mode PWM Control Circuit
Reflow (SMD styles only) ...........60 sec. max above 183°C, 230°C peak
34V
8.4V/7.6V
Amplifier
2 R
Error
V
FB
R
CC
Oscillator
CC
+
-
, V
Undervoltage Lock-out
<30mA) ..........................................................Self Limiting
with 50% Max Duty Cycle
2.50V
SENSE
Absolute Maximum Ratings
1V
Description
Comparator
)...........................................................-0.3V to 5.5V
Sensing
Current
R
R
Block Diagram
Undervoltage
Reset
Set/
Flip-Flop
Lockout
Toggle
V
R
S
PWM
Latch
REF
Reference
5.0 Volt
An undervoltage lockout ensures
that V
output stage is enabled. In the
CS52845 turn on is at 8.4V and
turn off at 7.6V.
Other features include low start-up
current, pulse-by-pulse current lim-
iting, and a high-current totem pole
output for driving capacitive loads,
such as gate of a power MOSFET.
The output is low in the off state,
consistent with N-channel devices.
CS52845
REF
NOR
is stabilized before the
Internal
Bias
1
V
V
V
Pwr Gnd
CC
REF
OUT
Pwr
2000 South County Trail, East Greenwich, RI 02818
N. American Technical Support: 800-282-9855
Tel: (401)885–3600 Fax: (401)885–5786
Web Site: www.cherry–semi.com
COMP
Sense
COMP
Optimized for Off-line
Control
Temperature
Compensated Oscillator
50% Maximum Duty-cycle
Clamp
V
Output Stage is Enabled
Low Start-up Current
Pulse-by-pulse Current
Limiting
Improved Undervoltage
Lockout
Double Pulse Suppression
1% Trimmed Bandgap
Reference
High Current Totem Pole
Output
Package Options
Sense
OSC
OSC
V
V
REF
NC
NC
NC
FB
FB
ON Semiconductor
14L SO Narrow
Features
8L SO Narrow
1
2
3
4
1
2
3
4
5
6
7
Stabilized before
5
14
13
12
10
8
7
6
11
9
8
V
V
V
Gnd
V
NC
V
V
V
Gnd
Pwr Gnd
REF
CC
OUT
CC
OUT
REF
CC
Pwr

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cs52845 Summary of contents

Page 1

... CS52845 An undervoltage lockout ensures that V is stabilized before the REF output stage is enabled. In the CS52845 turn 8.4V and turn off at 7.6V. Other features include low start-up current, pulse-by-pulse current lim- iting, and a high-current totem pole output for driving capacitive loads, such as gate of a power MOSFET. ...

Page 2

Electrical Characteristics: -40 T 85° PARAMETER Reference Section Output Voltage T =25° Line Regulation 12 V Load Regulation 1 I Temperature Stability (Note 2) Total Output Variation Line, Load, Temp. (Note 2) Output Noise Voltage 10Hz ...

Page 3

Electrical Characteristics: Unless otherwise stated, specifications apply for -40 T PARAMETER Total Standby Current Start-Up Current Operating Supply Current V V Zener Voltage PWM Section Maximum Duty Cycle Minimum Duty Cycle Undervoltage Lockout Section Start Threshold Min. ...

Page 4

... Adjust 5k 4.7k Sense Adjust 8. 7.6V OFF I CC <15mA <1mA V ON Figure 1: Startup voltage for the CS52845. Test Circuit Open Loop Laboratory Test Fixture R T COMP V REF Sense OUT OSC Gnd C T Circuit Description During Undervoltage Lockout (Figure 1), the output driv biased to sink minor amounts of current ...

Page 5

V OSC OSC RESET Toggle F/F Output EA Output Switch Current Figure 2: Timing Diagram V upper V lower +2t off c ...

Page 6

... SO Narrow 8.75 1.27 (.050) 0.40 (.016) REF: JEDEC MS-012 Ordering Information Part Number Description CS52845ED8 8L SO Narrow CS52845EDR8 8L SO Narrow (tape & reel) CS52845ED14 14L SO Narrow CS52845EDR14 14L SO Narrow (tape & reel) Package Specification Thermal Data D English R JC Min Max Min R JA 4.80 .197 ...

Page 7

Notes ...

Page 8

Notes ...

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