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MIK384x Series
CURRENT-MODE PWM CONTROLLERS
1
DATA SHEET
29 A
UGUST
2003
N
O
. 00016
R
EV
1-03
CONTENTS
Page
GENERAL DESCRIPTION
1
FEATURES
1
PIN CONNECTION
AND
DESCRIPTION
2
BLOCK DIAGRAM
2
ABSOLUTE MAXIMUM RATINGS
3
ELECTRICAL CHARACTERISTICS
3
APPLICATION INFORMATION
4
OPEN-LOOP LABORATORY TEST FIXTURE
4
UNDER VOLTAGE LOCKOUT (UVLO)
4
ERROR AMPLIFIER CONFIGURATION
5
CURRENT SENSE CIRCUIT
5
OSCILLATOR WAVEFORMS AND MAXIMUM
DUTY CYCLE
5
OSCILLATOR DEAD TIME
VS.
C
T
5
CONTENTS
Page
TIMING RESISTANCE vs. FREQUENCY
5
SHUTDOWN TECHNIQUES
6
SLOPE COMPENSATION
6
THERMAL DATA
6
POWER DISSIPATION CURVE
6
TYPICAL PERFORMANCE CHARACTERISTICS
7
V
REF
TEMPERATURE DRIFT
7
I
START
TEMPERATURE DRIFT
7
I
CC
TEMPERATURE DRIFT
7
PHYSICAL DIMENSIONS AND MARKING
DIAGRAMS
8
DIP-8
8
SOP-8
8
SOP-14
8
ORDERING INFORMATION
9
GENERAL DESCRIPTION
The MIK3842A(AM)(BW)/43A(AM)(BW)/44A(AM)
(BW)/45A(AM)(BW) are fixed frequency current
mode PWM controller. They are specially designed
for OFF-Line and DC to DC converter applications
with a minimal external components. Internally
implemented circuits include a trimmed oscillator
for precise duty cycle control, a temperature
compensated reference, high gain error amplifier,
current sensing comparator, and a high current
totempole output ideally suited for driving a power
MOSFET. Protection circuitry includes built
undervoltage lockout and current limiting.
The MIK3842A(AM)(BW) and MIK3844A(AM)(BW) have
UVLO thresholds of 16V (ON) and 10V (OFF). The
corresponding thresholds for the MIK3843A(AM)
(BW)/45A(AM)(BW) are 8.4V (ON) and 7.6V (OFF). The
MIK3842A(AM)(BW) and MIK3843A(AM)(BW) can
operate within 100% duty cycle. The MIK3844A(AM)
(BW) and MIK3845A(AM)(BW) can operate within 50%
duty cycle.
The MIK384xA(AM)(BW) has Start-Up Current 0.17mA
(typ).
The MIK384xA-BW are revised UC384xAM and differ
by higher Unity Gain bandwidth of Error Amplifier.
FEATURES
Low Start-Up and Operating Current
High Current Totem Pole Output
Undervoltage Lockout With Hysteresis
Operating Frequency Up To
300kHz for 384xA
500kHz for 384xAM, 384xBW
REPLACEMENT
of
UC384
X
MIK384x series
CURRENT MODE PWM CONTROLLER
2
Design by Vladimir F.Lityaghin / E-mail: lityaghin@mail.ru / Tel: +7(095)532-64-54
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CURRENT-MODE PWM CONTROLLERS
MIK384x Series
BLOCK
DIAGRAM
PIN CONNECTION
AND
DESCRIPTION
PIN
SYMBOL
DESCRIPTION
8-PIN
14-PIN
1
1
COMP
This pin is the Error Amplifier output and
is made for loop compensation.
2
3
V
FB
This is the inverting input of the Error
Amplifier. It is normally connected to the
switching power supply output through a
resistor divider.
3
5
V
SENSE
A voltage proportional to inductor current
is connected to this input. The PWM uses
this information to terminate the output
switch conduction.
4
7
R
T
/C
T
The oscillator frequency and maximum
output duty cycle are programmed by
connecting resistor R
T
to V
ref
and
capacitor C
T
to ground.
5
--
GND
This pin is the combined control circuitry
and power ground.
6
10
OUT
This output directly drives the gate of a
power MOSFET. Peak currents up to 1A
are sourced and sink by this pin.
7
12
V
CC
This pin is the positive supply of the
integrated circuit.
8
14
V
REF
--
8
P_GND
This pin is a separate power ground return
(14pin package only) that is connected
back to the power source. It is used to
reduce the effects of switching transient
noise on the control circuitry.
--
11
P_V
C
The output high state (V
OH
) is set by the voltage applied to this pin (14pin package only).
With a separate power source connection, it can reduce the effects of switching transient
noise on the control circuitry.
--
9
GND
This pin is the control circuitry ground return (14pin package only) and is connected back
to the power source ground.
--
2, 4,
6, 13
NC
No connection (14-pin package only). These pins are not internally connected.
This is the reference output. It provides
charging current for capacitor C
T
through
resistor R
T
.
MIK384xN, MIK384x-BWN
DIP-8
1 -- COMP
2 -- V
FB
3 -- V
SENSE
4 -- R
T
/C
T
5 -- GND
6 -- OUT
7 -- V
CC
8 -- V
REF
MIK384xD1, MIK384x-BWD1
SOP-8
1 -- COMP
2 -- V
FB
3 -- V
SENSE
4 -- R
T
/C
T
5 -- GND
6 -- OUT
7 -- V
CC
8 -- V
REF
SOP-14
1 -- COMP
2 --
NC
3 -- V
FB
4 --
NC
5 -- V
SENSE
6 --
NC
7 -- R
T
/C
T
8 -- P_GND
9 -- GND
10 -- OUT
11 -- V
CC
12 -- V
CC
13 --
NC
14 -- V
REF
MIK384xD, MIK384x-BWD
4
1
8
5
1
4
8
5
A
= DIP-8 and
SOP-8 Pin Number.
B
= SOP-14 Pin Number.
Toggle flip flop used only
in MIK3844 and MIK3845.
NOTES:
!
A
B
1
7
14
8
SET/
RESET
5V
Reference
!
3
5
!
1
1
!
2
3
!
!
!
!
!
UVLO
Under-Voltage
Lockout (
)
16V
34V
6V
2.5V
Current
Sense
Comparator
Latching
PWM
Error
Amplifier
Internal
Bias
V
FB
V
SENSE
V
CC
V
REF
R
T
/C
T
COMP
OUT
P_GND
GND
S
R
T
2R
R
1V
!
!
!
7
12
4
7
5
9
P_V
C
!
7
11
!
8
14
!
6
10
!
5
8
Oscillator
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MIK384x Series
CURRENT-MODE PWM CONTROLLERS
3
* Adjust V
CC
above the start threshold before setting it to 15V.
ABSOLUTE MAXIMUM RATINGS
SYMBOL
CHARACTERISTIC
VALUE
UNIT
V
CC
Supply Voltage (low impedance source)
30
V
I
O
Output Current
1
A
V
I
Input Voltage (Analog Inputs pins 2,3)
-0.3 to 5.5
V
I
SINK (E.A)
Error Amp Output Sink Current
10
mA
P
O
Power Dissipation (T
A
= 25
0
C) 1
W
Tstg
Storage Temperature Range
-65 to150
o
C
T
L
Lead Temperature (soldering 5 sec.)
260
o
C
SYMBOL
CHARACTERISTICS
TEST CONDITION
MIN
TYP
MAX
UNIT
R
EFERENCE
S
ECTION
V
REF
Reference Output Voltage
T
J
= 25C, I
REF
= 1 mA
4.9 5.0 5.1 V
V
REF
Line Regulation
12V V
CC
25 V
-- 6.0 20 mV
I
REF
Load Regulation
1 mA I
REF
20mA
-- 6.0 25 mV
I
SC
Short Circuit Output Current
T
A
= 25C
-- -100
-180 mA
O
SCILLATOR
S
ECTION
T
J
= 25C (MIK384x-A)
47 50 57 kHz
f
Oscillation Frequency
T
J
= 25C (MIK384x-AM,
MIK384x-BW)
47 52 57 kHz
f/V
CC
Frequency Change with Voltage
12V V
CC
25 V
-- 0.05 1.0 %
V
(OSC)
Oscillator Amplitude
(peak to peak)
--
1.6
--
V
E
RROR
A
MPLIFIER
S
ECTION
I
BIAS
Input Bias Current
V
FB
=3V
-0.1
-2
A
V
I(E.A)
Input Voltage
V
PIN 1
= 2.5V
2.42
2.5
2.58
V
A
VOL
Open Loop Voltage Gain
2V V
0
4V
65 90 -- dB
UGBW
Unity Gain Bandwidth (only for
MIK384xA-BW)
T
j
=25
0
C, Note 3
0.5
0.6
--
MHz
PSRR
Power Supply Rejection Ratio
12V V
CC
25 V
60 70 -- dB
I
SINK
Output Sink Current
V
PIN 2
= 2.7V, V
PIN 1
= 1.1V
2
7
--
mA
I
SOURCE
Output Source Current
V
PIN 2
= 2.3V, V
PIN 1
= 5V
-0.5
-1.0
--
mA
V
OH
High Output Voltage
V
PIN 2
= 2.3V, R
L
= 15k to GND
5.0 6.0 -- V
V
OL
Low Output Voltage
V
PIN 2
= 2.7V, R
L
= 15k to Pin8
-- 0.8 1.1 V
C
URRENT
S
ENSE
S
ECTION
G
V
Gain
(Notes 1, 2)
2.85
3.0
3.15
V/V
V
I(MAX)
Maximum Input Signal
V
PIN 1
= 5V (Note1)
0.9
1.0
1.1
V
SVR
Supply Voltage Rejection
12V V
CC
25V (Note 1)
-- 70 -- dB
I
BIAS
Input Bias Current
V
PIN 3
= 3V
--
-3.0
-10
A
O
UTPUT
S
ECTION
I
SINK
= 20 mA
--
0.08
0.4
V
OL
Low Output Voltage
I
SINK
= 200 mA
--
1.4
2.2
V
I
SINK
= 20 mA
13
13.5
--
V
OH
High Output Voltage
I
SINK
= 200 mA
12
13.0
--
V
t
R
Rise Time
T
J
= 25C, C
L
= 1nF (Note 3)
-- 45 150
t
F
Fall Time
T
J
= 25C, C
L
= 1nF (Note 3)
-- 35 150
ns
ELECTRICAL CHARACTERISTICS
(* V
CC
=15V, R
T
= 10K
, C
T
= 3.3nF, T
A
= 0
0
C TO +70
0
C, unless otherwise specified)
4
Design by Vladimir F.Lityaghin / E-mail: lityaghin@mail.ru / Tel: +7(095)532-64-54
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m
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29 A
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003
CURRENT-MODE PWM CONTROLLERS
MIK384x Series
ELECTRICAL CHARACTERISTICS
(CONTINUED)
(* V
CC
= 15V, R
T
= 10K
, C
T
= 3.3nF, T
A
= 0
0
C TO +70
0
C, unless otherwise specified)
* Adjust V
CC
above the Startup threshold before setting it to 15V.
Note 1: Parameter measured at trip point of latch with V
pin2
= 0.
Note 2: Gain defined as A = V
pin1
/V
pin3
; 0
V
pin3
0.8V.
Note 3: These parameters, although guaranteed, are not 100% tested in production.
SYMBOL
CHARACTERISTICS
TEST CONDITION
MIN
TYP
MAX
UNIT
U
NDERVOLTAGE
L
OCKOUT
S
ECTION
MIK3842A(AM), MIK3842A-BW
MIK3844A(AM), MIK3844A-BW
14.5 16.0 17.5 V
MIK3843A(AM), MIK3843A-BW
V
TH(ST)
Start Threshold
MIK3845A(AM), MIK3845A-BW
7.8 8.4 9.0 V
MIK3842A(AM), MIK3842A-BW
MIK3844A(AM), MIK3844A-BW
8.5 10 11.5 V
MIK3843A(AM), MIK3843A-BW
V
OPR(min)
Min. Operating Voltage (After
Turn On)
MIK3845A(AM), MIK3845A-BW
7.0 7.6 8.2 V
PWM S
ECTION
MIK3842A(AM), MIK3842A-BW
MIK3843A(AM), MIK3843A-BW
95 97 100 %
MIK3844A(AM), MIK3844A-BW
D
(MAX)
Max. Duty Cycle
MIK3845A(AM), MIK3845A-BW
47 48 50 %
D
(MIN)
Min. Duty Cycle
--
--
--
0
%
T
OTAL
S
TANDBY
C
URRENT
I
ST
Start-Up Current
MIK384xA(AM), MIK384xA-BW
0.17
0.3
I
CC (OPR)
Operating Supply Current
V
pin3
= V
pin2
= 0V
13
17
mA
V
Z
Zener Voltage
I
CC
=25 mA
30
38
V
APPLICATION INFORMATION
OPEN-LOOP LABORATORY TEST FIXTURE
High peak currents 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
waveform and a pply an
adjustable ramp to pin 3.
UNDERVOLTAGE LOCKOUT (UVLO)
During Under-Voltage Lock-Out,
the output driver is biased to a
high impedance state. Pin 6
should be shunted to ground with
a bleeder resistor to prevent
activating the power switch with
output leakage current.
!
4.7k
CT
I
Adjust
SENSE
Error
Amp
Adjust
RT
100k
5k
4.7k
0.1F
0.1F
1k /1W
V
REF
V
CC
V
OUT
A
!
!
!
!
!
!
!
!
1
8
2
7
3
6
4
5
!
!
!
!
!
!
7
ON/OFF Command
to rest of IC
V
CC
V
CC
V
CC
V
OFF
V
ON
<15mA
<0.3mA
V
ON
= 16V
V
OFF
= 10V
!
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MIK384x Series
CURRENT-MODE PWM CONTROLLERS
5
APPLICATION INFORMATION
(CONTINUED)
ERROR AMPLIFIER CONFIGURATION
Error amplifier can source or sink up
to 0.5A.
CURRENT SENSE CIRCUIT
Peak current (IS) is determined by the
formula:
I
S
(MAX) = 1V / R
S
A small RC filter may be required to
suppress switch transients.
OSCILLATOR WAVEFORMS
AND
MAXIMUM DUTY CYCLE
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 the output
to the low state. Selection of R
T
and
C
T
therefore determines both
oscillator frequency and maximum
duty cycle. Charge and discharge
times are determined by the formulas:
tc = 0.55 R
T
C
T
Frequency, then, is
f = (tc + td)
-1
For
R
T
> 5k
f
1.8 /
R
T
C
T
OSCILLATOR DEAD TIME
VS.
C
T
(R
T
> 5K)
TIMING RESISTANCE
VS.
FREQUENCY
!
!
!
2
1
Zi
Zf
0.5mA
2.5V
Current Sense
Comparator
Error
Amplifier
1V
R
R
C
R
S
I
S
2R
!
!
!
1
3
5
!
INTERNAL
CLOCK
INTERNAL
CLOCK
SMALL
LARGE
R
C
T
T
SMALL
LARGE
R
C
T
T
R
T
C
T
V4
V4
!
!
!
5
4
8
V
REF
R C
T
T
/
GND
-
-
4
0063
0
7
2
0063
0
T
T
T
T
R
.
.
R
.
ln
C
R
td
0.1
1
1
10
100
10
td
(
s)
C
T
(nF)
100
10
R
T
(k
)
100
10
6
10
5
10
4
10
3
10
2
FREQUENCY (Hz)
1
C
T
=
nF
1
C
T
=
nF
2.
2
C
T
=
nF
4.
7
C
T
=
nF
10
C
T
=
nF
22
C
T
=
nF
47
C
T
=
nF
10
0
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