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 J, N Packages
Derate @ Tamb > 50°C
PDPower Dissipation Tcase = 25°C D Package
Derate @ Tamb > 50°C
PDPower Dissipation Tcase = 25°C J, N Packages
Derate @ Tcase > 25°C
TSTG Storage Temperature Range
TLLead Temperature (soldering, 10 seconds)
+30V
Self limiting
±1A
5µJ
–0.3V to +VCC
10mA
1W
10mW/°C
725mW
7.25mW/°C
2W
16mW/°C
–65 to 150°C
+300°C
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
ABSOLUTE MAXIMUM RATINGS (Tcase = 25°C unless otherwise stated)
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IP1842A SERIES
IP1843A SERIES
Semelab plc. Telephone (01455) 556565. Telex: 341927. Fax (01455) 552612. Prelim. 2/95
CURRENT MODE
REGULATING
PULSE WIDTH
MODULATORS
FEATURES
• Guaranteed ±1% reference voltage tolerance
• Accurate oscillator discharge current
• Guaranteed ±10% frequency tolerance
• Low start–up current (<500
m
A)
• Under voltage lockout with hysteresis
• Output state completely defined for all supply
and input conditions
• Interchangeable with IP and UC1842/3 series for
improved operation
• 500kHz Oscillator operation
Part J–Pack N–Pack D–8 D–14 Temp.
Number 8 Pin 8 Pin 8 Pin 14 Pin Range
IP1842A ✔-55 to +125°C
IP2842A ✔✔✔✔-25 to +85°C
IP3842A ✔✔✔✔0 to +70°C
IP1843A ✔-55 to +125°C
IP2843A ✔✔✔✔-25 to +85°C
IP3843A ✔✔✔✔0 to +70°C
Order Information Note:
To order, add the package identifier to the
part number.
eg. IP1842AD–14
IP3843AJ
* 1844A and 1 845A series only.
Values in brackets are for IP1845 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
LAT CH
REF
PIN NUMBERS
1st Number
2nd Number – N, J and 8 P in D Packa ges
– 14 Pin D P ackage.
C
OMP
G
ND
V
CC
I
SENSE
V
FB
/CR
TT
OUTPUT
POWER
GROUND
V
RE F
V
C
3/5
5/9
7/12
2/3
1/1
4/7 6/10
7/11
5/8
8/14
TOGGLE
FLIP
FLOP *
T
Q
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IP1843A SERIES
Semelab plc. Telephone (01455) 556565. Telex: 341927. Fax (01455) 552612. Prelim. 2/95
VCC Supply Voltage 1
IOOutput Current
Analog Inputs (pins 2 and 3)
Error Amp Output Sink Current IP1842A , IP1843A
Operating Ambient Temperature Range IP2842A , IP2843A
IP3842A , IP3843A
≤ 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.
DESCRIPTION
The IP1842A/IP1843A 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 standard IP1842/3 parts these devices offer improved performance in several
areas. They also offer tighter specification and improved performance over the IP and UC1842/3 series, whilst
retaining complete compatibility.
BLOCK DIAGRAM
RECOMMENDED OPERATING CONDITIONS
NOTES
1. Test Conditions unless otherwise stated:
VCC = 15V* , RT= 10kΩ, CT= 3.3nF , f = 52kHz.
*Adjust VCC above start threshold before setting at required level.
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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
7.8 8.3 8.8
79
2.42 2.50 2.58
–0.3 –2
65 90
0.7 1
60 70
26
–0.5 –0.8
4.6 6
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
7.8 8.3 8.8
79
2.45 2.50 2.55
–0.3 –1
65 90
0.7 1
60 70
26
–0.5 –0.8
4.6 6
0.7 1.1
IP1842A , IP1843A IP3842A
IP2842A , IP2843A IP3843A
Parameter Test Conditions 1Min. 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
∆TA= Min to Max
VPIN4 Peak to Peak
TJ= 25°C
∆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 = 5V
VPIN2 = 2.3V RL= 15kΩ
VPIN2 = 2.7V RL= 15kΩ
V
mV
mV°C
V
µV
mV
mA
kHz
%
%
V
mA
V
µA
dB
MHz
dB
mA
V
ELECTRICAL CHARACTERISTICS (Over Full Operating Temperature Range unless otherwise stated)
REFERENCE SECTION
OSCILLATOR SECTION
ERROR AMP SECTION
All specifications apply over the full operating temperature range unless otherwise stated.
(See Ordering Information for further details).
IP1842A , IP1843A IP3842A
IP2842A , IP2843A IP3843A
Parameter Test Conditions 1Min. Typ. Max. Min. Typ. Max. Units
2.85 3 3.15
0.9 1 1.1
60 70
–2 –10
150 300
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
95 97 100
0
2.85 3 3.15
0.9 1 1.1
60 70
–2 –10
150 300
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
95 97 100
0
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
Maximum Duty Cycle
Minimum Duty Cycle
See Notes 2,3
VPIN1 = 5V (Note 2)
VC= 12V to 25V
ISINK = 20mA
ISINK = 200mA
ISOURCE = 20mA
ISOURCE = 200mA
CL= 1nF
CL= 1nF
VCC = 6V IL= 1mA
IP1842A Series
IP1843A Series
IP1842A Series
IP1843A Series
VPIN2 = 0V IP1842A Series
VPIN3 = 0V IP1843A Series
ICC = 25mA
V/V
V
dB
µA
ns
V
V
ns
V
V
V
mA
mA
V
%
NOTES
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Semelab plc. Telephone (01455) 556565. Telex: 341927. Fax (01455) 552612. Prelim. 2/95
ELECTRICAL CHARACTERISTICS (Over Full Operating Temperature Range unless otherwise stated)
CURRENT SENSE SECTION
OUTPUT SECTION
UNDER–VOLTAGE LOCKOUT SECTION
TOTAL STANDBY CURRENT
PWM SECTION
1. Test Conditions unless otherwise stated:
VCC = 15V* , RT= 10kΩ, 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: ∆VPIN1
A = ∆VPIN3
0 ≤VPIN3 ≤0.8
tc≈0.55 RTCT
td≈RTCTRn
1
Resultant frequency f = (tc+ td)
For RT> 5kΩ,
1.8
Resultant frequency f ≈(RTCT)
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Open–Loop Laboratory Test Fixture
APPLICATIONS INFORMATION
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:
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.
0.1
µ
F
1k
Ω
1kW
1k
Ω
ERROR AMP
ADJUST
4.7k
Ω
5k
Ω
ADJUST
4.7k
Ω
100k
Ω
2N2222
I
SENSE
R
T
C
T
0.1
µ
F
V
REF
V
CC
OUTPUT
GROUND
1
2
45
7
8
36
I
SENSE
V
REF
V
CC
O/P
GND
COMP
V
FB
R
T
/C
T
Oscillator Waveforms and Maximum Duty Cycle
8
4
5
GND
R
T
C
T
REF
V
R
T
C
T
PIN4
V (V for 14 pin D package)
PIN7
INTERNAL CLOCK
INTERNAL CLOCK
OUTPUT – Max. Duty Cycle
PIN6
V (V for 14 pin D package)
PIN10
PIN4
V (V for 14 pin D package)
PIN7
OUTPUT – Max. Duty Cycle
PIN6
V (V for 14 pin D package)
PIN10
LARGE C
T
SMALL R
T
LARGE R
T
SMALL C
T
.0063 RT– 2.3
.0063 – 4
( )
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IP1843A SERIES
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.01 .02 .04 .07 .1 .2 .4 .7 1.0
4
3
2
1
0
60
40
20
0
100
80
10 1k100 10k 10M100k 1M
.05 .5.03 .3
OUTPUT CURRENT, SOURCE / SINK (A) FREQUENCY (Hz)
SATUR ATIO N VOL TAGE (V)
VO LTAGE GAIN (dB)
OUTPUT SATURATION CHARACTERISTICS ERROR AMPLIFIER OPEN-LOOP
FREQUENCY RESPONSE
V = 15V
CC
T = 25˚C
A
A
V
f
SOURCE SAT V - )
CC
V
OH
SINK SAT (V )
OL
(
A
T = –55˚C –45
–90
–135
–180
0
PHASE (˚)
TYPICAL PERFORMANCE CHARACTERISTICS
