IP1842 SERIES
IP1843 SERIES
Prelim.3/00
Semelab plc. Telephone +44(0)1455 556565. Fax +44(0)1455 552612.
E-mail: sales@semelab.co.uk Website: http://www.semelab.co.uk
CURRENT MODE
REGULATING
PULSE WIDTH
MODULATORS
FEATURES
• Guaranteed ±1% reference voltage tolerance
• Guaranteed ±10% frequency tolerance
• Low start–up current (<500
mm
mm
A)
• Under voltage lockout with hysteresis
• Output state completely defined for all supply
and input conditions
• Interchangeable with UC1842 and UC1843
series for improved operation
• 500kHz operation
VCC Supply Voltage (low impedance source)
(ICC < 30mA)
IOOutput Current
Output Energy (capacitive load)
Analog Inputs (pins 2 and 3)
Error Amp Output Sink Current
PDPower Dissipation Tamb = 25°C
Derate @ Tamb > 50°C
PDPower Dissipation Tcase = 25°C
Derate @ Tcase > 25°C
TSTG Storage Temperature Range
TLLead Temperature (soldering, 10 seconds)
+30V
Self limiting
±1A
5
m
J
–0.3V to +VCC
10mA
1W
10mW/°C
2W
24mW/°C
–65 to 150°C
+300°C
ABSOLUTE MAXIMUM RATINGS (Tcase = 25°C unless otherwise stated)
TOP VIEW
J Package – 8 Pin Ceramic DIP
N Package – 8 Pin Plastic DIP
D-8 Package – 8 Pin Plastic (150) SOIC
1
2
3
4
8
7
6
5
COMP V
REF
GROUND
OUTPUT
R
T
/C
T
V
CC
I
SENSE
V
FB
TOP VIEW
D-14 Package – 14 Pin Plastic (150) SOIC
COMP V
REF
GROUND
OUTPUT
1
2
3
4
POWER
GROUND
5
6
7
14
13
12
11
10
9
8
N/C
R
T
/C
T
I
SENSE
N/C
N/C N/C
V
CC
V
FB
V
C
Part J–Pack N–Pack D–8D–14 Temp.
Number 8 Pin 8 Pin 8 Pin 14 Pin Range
IP1842 ✔-55 to +125°C
IP2842 ✔✔✔✔-25 to +85°C
IP3842 ✔✔✔✔0 to +70°C
IP1843 ✔-55 to +125°C
IP2843 ✔✔✔✔-25 to +85°C
IP3843 ✔✔✔✔0 to +70°C
Order Information Note:
To order, add the package identifier to the
part number.
eg. IP1842J
IP3843D-14
IP1842 SERIES
IP1843 SERIES
Prelim.3/00
Semelab plc. Telephone +44(0)1455 556565. Fax +44(0)1455 552612.
E-mail: sales@semelab.co.uk Website: http://www.semelab.co.uk
DESCRIPTION
The IP1842 and IP1843 series of switching regulator control circuits contain all the functions necessary to
implement off–line, current mode switching regulators, using a minimum number of external parts. Functions
included are voltage reference, error amplifier, current sense comparator, oscillator, totem pole output driver and
under-voltage lockout circuitry.
Although pin compatible with the UC1842 and 1843 series, SEMELAB has incorporated several improvements in
the IP1842 and IP1843 series allowing tighter and more complete specification of electrical performance.
BLOCK DIAGRAM
Values in brackets are for IP1843 series.
3.6V
ERROR
AMP
OSCILLATOR
2R
R1V R
S
PWM
LATCH
CURRENT
SENSE
COMPARATOR
16V
(8.4V) 6V
(0.5V) 2.5V
UNDER–VOLTAGE
LOCKOUT
ENABLE REFERENCE
REGULATOR 5V
INTERNAL
BIAS
34V
REG
R
SV STATUS
LATCH
REF
OUTPUT
V
RE F
C
OMP
G
ND
V
CC
I
SENSE
V
FB
/CR
TT
POWER
GROUND
V
C
PIN NUMBERS
1st Number
2nd Number – N, J and 8 Pin D Packages
– 14 Pin D Pa ckage.
3/5
5/9
7/12
2/3
1/1
4/7 6/10
7/11
5/8
8/14
VCC Supply Voltage 1
IOOutput Current
Analog Inputs (pins 2 and 3)
Error Amp Output Sink Current IP1842 , IP1843
Operating Ambient Temperature Range IP2842 , IP2843
IP3842 , IP3843
£
30V
0 to ±200mA
–0.3V to 3V
0 to 2mA
–55 to 125°C
–25 to 85°C
0 to 70°C
Notes:
1. Lower limit set by under voltage lockout specification.
RECOMMENDED OPERATING CONDITIONS
NOTES
1. Test Conditions unless otherwise stated:
VCC = 15V* , RT= 10k
W
, CT= 3.3nF , f = 52kHz.
*Adjust VCC above start threshold before setting at required level.
All specifications apply over the full operating temperature range
unless otherwise stated. (See Ordering Information for further details).
IP1842 SERIES
IP1843 SERIES
Prelim.3/00
Semelab plc. Telephone +44(0)1455 556565. Fax +44(0)1455 552612.
E-mail: sales@semelab.co.uk Website: http://www.semelab.co.uk
4.90 5.00 5.10
620
625
0.2 0.4
4.82 5.18
50
525
30 80 160
47 52 57
0.2 1
5
1.7
8.3
8
2.42 2.50 2.58
–0.3 –2
65 90
0.7 1
60 70
26
–0.5 –0.8
4.6 4.8
0.7 1.1
4.95 5.00 5.05
620
625
0.2 0.4
4.90 5.10
50
525
30 80 160
47 52 57
0.2 1
5
1.7
8.3
8
2.45 2.50 2.55
–0.3 –1
65 90
0.7 1
60 70
26
–0.5 –0.8
4.6 4.8
0.7 1.1
IP1842/IP1843 IP3842
IP2842/IP2843 IP3843
Parameter Test Conditions Min. Typ. Max. Min. Typ. Max. Units
Output Voltage
Input Regulation
Output Regulation
Temperature Stability
Total Output Variation
Output Noise Voltage
Long Term Stability
Output Short Circuit
Current
Frequency
Voltage stability
Temperature Stability
Amplitude
Discharge Current
Input Voltage
Input Bias Current
Open Loop Voltage
Gain
Unity Gain Bandwidth
Supply Voltage
Rejection
Output Sink Current
Output Source Current
VOUT High
VOUT Low
IO= 1mA TJ= 25°C
VCC = 12V to 25V
IO= 1mA to 20mA
Line, Load, Temp
f = 10Hz to 10kHz TJ= 25°C
TJ= 125°C @ 1000Hrs
VREF = 0
TJ= 25°C
VCC = 12V to 25V
D
TA= Min to Max
VPIN4 Peak to Peak
TJ= 25°C
D
TA= Min to Max
VPIN1 = 2.5V
VO= 2V to 4V
VCC = 12V to 25V
VPIN2 = 2.7V VPIN1 = 1.1V
VPIN2 = 2.3V VPIN1 = 4.6V
VPIN2 = 2.3V RL= 15k
W
VPIN2 = 2.7V RL= 15k
W
V
mV
mV°C
V
m
V
mV
mA
kHz
%
%
V
mA
%
V
m
A
dB
MHz
dB
mA
V
ELECTRICAL CHARACTERISTICS (Over Full Operating Temperature Range unless otherwise stated)
REFERENCE SECTION
OSCILLATOR SECTION
ERROR AMP SECTION
IP1842/IP1843 IP3842
IP2842/IP2843 IP3843
Parameter Test Conditions Min. Typ. Max. Min. Typ. Max. Units
2.85 3 3.15
0.911.1
60 70
–2–10
200 400
0.1 0.4
1.5 2.2
13 13.5
12 13.5
50 150
50 150
0.7 1.1
14.5 16 17.5
7.8 8.4 9
8.5 10 11.5
7 7.6 8.2
0.3 0.5
11 15
14 17
30 34 40
2.85 3 3.15
0.911.1
60 70
–2–10
200 400
0.1 0.4
1.5 2.2
13 13.5
12 13.5
50 150
50 150
0.7 1.1
15 16 17
7.8 8.4 9
91011
7 7.6 8.2
0.3 0.5
11 15
14 17
30 34 40
Gain
Maximum Input Signal
Supply Voltage
Rejection
Input Bias Current
Delay to Output
Output Low Level
Output High Level
Rise Time
Fall Time
UVLO Saturation
Upper Threshold
(VCC)
Lower Threshold
(VCC)
Start–up Current
Operating Supply
Current
VCC Zener Voltage
See Notes 2,3
VPIN1 = 4.6V (Note 2)
VC= 12V to 25V
ISINK = 20mA
ISINK = 200mA
ISOURCE = 20mA
ISOURCE = 200mA
CL= 1nF TJ= 25°C
CL= 1nF TJ= 25°C
VCC = 6V IL= 1mA
1842 Series
1843 Series
1842 Series
1843 Series
VPIN2 = 0V 1842 Series
VPIN3 = 0V 1843 Series
ICC = 25mA
V/V
V
dB
m
A
ns
V
V
ns
V
V
V
mA
mA
V
NOTES
1. Test Conditions unless otherwise stated:
VCC = 15V* , RT= 10k
W
, CT= 3.3nF , f = 52kHz.
*Adjust VCC above start threshold before setting at
required level.
All specifications apply over the full operating temperature
range unless otherwise stated.
(See Ordering Information for further details).
2. Parameter measured at trip point of latch with
VPIN2 = 0V
3. Gain defined as:
D
VPIN1
A =
D
VPIN3
0
£
VPIN3
£
0.8
IP1842 SERIES
IP1843 SERIES
Prelim.3/00
Semelab plc. Telephone +44(0)1455 556565. Fax +44(0)1455 552612.
E-mail: sales@semelab.co.uk Website: http://www.semelab.co.uk
ELECTRICAL CHARACTERISTICS (Over Full Operating Temperature Range unless otherwise stated)
CURRENT SENSE SECTION
OUTPUT SECTION
UNDER–VOLTAGE LOCKOUT SECTION
TOTAL STANDBY CURRENT
tc
»
0.55 RTCT
td
»
RTCTRn
1
Resultant frequency f = (tc+ td)
For RT> 5k
W
,
1.8
Resultant frequency f
»
(RTCT)
Oscillator timing capacitor CTis charged by VREF
through RTand discharged by an internal current source.
During the discharge time, the internal clock signal
blanks the output to the low state. Selection of RTand
CTtherefore determines both oscillator frequency and
maximum duty cycle. Charge and discharge times are
determined by the formulae:
.0063 RT– 2.3
.0063 – 4
( )
IP1842 SERIES
IP1843 SERIES
Prelim.3/00
Semelab plc. Telephone +44(0)1455 556565. Fax +44(0)1455 552612.
E-mail: sales@semelab.co.uk Website: http://www.semelab.co.uk
Open–Loop Laboratory Test Fixture
APPLICATIONS INFORMATION
High peak current associated with capacitive loads necessitate careful grounding techniques. Timing and bypass capacitors should
be connected close to pin 5 in a single point ground. The transistor and 5K potentiometer are used to sample the oscillator wave
form and apply an adjustable ramp to pin 3.
1
2
3
4
8
7
6
5
COMP V
REF
GROUND
OUTPUT
R
T
/C
T
V
CC
I
SENSE
V
FB
COMP V
REF
GROUND
OUTPUT
1
2
3
4
POWER
GROUND
5
6
7
14
13
12
11
10
9
8
N/C
R
T
/C
T
I
SENSE
N/C
N/C N/C
V
CC
V
FB
V
C
Oscillator Waveforms and Maximum Duty Cycle
IP1842 SERIES
IP1843 SERIES
Prelim.3/00
Semelab plc. Telephone +44(0)1455 556565. Fax +44(0)1455 552612.
E-mail: sales@semelab.co.uk Website: http://www.semelab.co.uk
1
2
3
4
8
7
6
5
COMP V
REF
GROUND
OUTPUT
R
T
/C
T
V
CC
I
SENSE
V
FB
TYPICAL PERFORMANCE CHARACTERISTICS
COMP V
REF
GROUND
OUTPUT
1
2
3
4
POWER
GROUND
5
6
7
14
13
12
11
10
9
8
N/C
R
T
/C
T
I
SENSE
N/C
N/C N/C
V
CC
V
FB
V
C
