Download UNISONIC TECHNOLOGIES CO., LTD UC3844/45

UNISONIC TECHNOLOGIES CO., LTD
UC3844/45
LINEAR INTEGRATED CIRCUIT
HIGH PERFORMANCE
CURRENT MODE PWM
CONTROLLERS
„
DESCRIPTION
The UTC UC3844/3845 are high performance fixed frequency
current mode controllers that specifically designed for Off-Line and
DC to DC converter applications with minimal external parts count.
The differences between UC3844 and UC3845 are the maximum
duty cycle ranges and under-voltage lockout thresholds. The
UC3844 ideally suited to off-line applications with UVLO thresholds
of 16V(ON) and 10V(OFF), and UC3845 has UVLO thresholds of
8.5V(ON) and 7.6V(OFF) for lower voltage applications.
„
FEATURES
* Operation output switching frequency up to 500 kHz
* Output deadtime adjustable from 50% to 70%
* Automatic feed forward compensation
* Latching PWM for cycle-by-cycle current limiting
* High current totem pole output
* Internally trimmed reference with under voltage lockout
* UVLO with hysteresis
* Low startup and operating current
„
ORDERING INFORMATION
Ordering Number
Lead Free
Halogen Free
UC3844L-D08-T
UC3844G-D08-T
UC3844L-S08-R
UC3844G-S08-R
UC3844L-S08-T
UC3844G-S08-T
UC3845L-D08-T
UC3845G-D08-T
UC3845L-S08-R
UC3845G-S08-R
UC3845L-S08-T
UC3845G-S08-T
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Copyright © 2012 Unisonic Technologies Co., Ltd
Package
Packing
DIP-8
SOP-8
SOP-8
DIP-8
SOP-8
SOP-8
Tube
Tape Reel
Tube
Tube
Tape Reel
Tube
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UC3844/45
PIN CONFIGURATION
„
PIN DESCRIPTION
„
PIN NO
1
2
3
4
5
6
7
8
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LINEAR INTEGRATED CIRCUIT
PIN NAME
FUNCTION
Compensation Error amplifier output, this pin is made available for loop compensation.
Voltage Feedback, the inverting input of the Error Amplifier. It is normally connected to the
VFB
switching power supply output through a resistor divider.
A voltage proportional to inductor current is connected to this input. The PWM uses this
ISENSE
information to terminate the output switch conduction.
The Oscillator frequency and maximum output duty cycle are programmed by connecting
RT/CT
resistor RT to Vref and capacitor CT to ground. Operation to 1 MHz is possible.
GND
Power ground.
This output directly drives the gate of a power MOSFET. Peak currents up to 1A are
Output
sourced and sunk by this pin. The output switches at one-half the oscillator frequency.
VCC
Positive supply.
VREF
Reference output, provides charging current for capacitor CT though resistor RT.
BLOCK DIAGRAM
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UC3844/45
„
LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATINGS (TA=25℃)
PARAMETER
SYMBOL
RATINGS
UNIT
Total Power Supply and Zener Current
(ICC+Iz)
30
mA
Output Current, Source or Sink (Note 2)
IOUT
1.0
A
Output Energy (Capacitive Load per cycle)
W
5.0
μJ
Current Sense and Voltage feedback Inputs
VIN
-0.3 ~ +5.5
V
Error Amp Output Sink Current
ISINK
10
mA
SOP-8
862
mW
Power Dissipation
PD
DIP-8
1250
mW
℃
Junction Temperature
TJ
+150
℃
Operation Temperature
TOPR
0 ~ 70
℃
Storage Temperature
TSTG
-65 ~ +150
Note:1.Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.
2.Maxmum package power dissipation limits must be observed.
„
THERMAL DATA
PARAMETER
Junction to Ambient
„
SYMBOL
SOP-8
DIP-8
θJA
RATINGS
145
100
UNIT
℃/W
℃/W
ELECTRICAL CHARACTERISTICS
(TA=25℃, VCC=15V, RT=10k, CT=3.3nF, 0℃ ≤ TA ≤
PARAMETER
SYMBOL
REFERENCE SECTION
Reference Output Voltage
VREF
△VOUT
Line Regulation
△VOUT
Load Regulation
Temperature Stability
Total Output Variation over Line,
Load, Temperature
Output Noise Voltage
Long Term Stability
Output Short Circuit Current
OSCILLATOR SECTION
Oscillator Voltage Swing
Discharge Current
VOSC
IDSG
Frequency
fOSC
Frequency Change with Voltage
Frequency Change with Temperature
ERROR AMPLIFIER SECTION
Voltage Feedback Input
High
Output Voltage Swing
Low
Sink
Output Current
Source
Input Bias Current
Open Loop Voltage Gain
Power Supply Rejection Ratio
Unity Gain Bandwidth
70℃, unless otherwise specified)
TEST CONDITIONS
MIN
IOUT=1.0mA,TJ=25℃
VCC=12V ~ 25V
IOUT=1.0mA ~ 20mA
tS
VREF
eN
S
ISC
ΔfOSC/ΔV
ΔfOSC/ΔT
VFB
VOH
VOL
ISINK
ISOURCE
II(BIAS)
GVO
PSRR
GBW
MAX
UNIT
5.0
2.0
3.0
0.2
5.1
20
25
V
mV
mV
mV/℃
5.18
V
-180
μV
mV
mA
4.82
f=10Hz ~ kHz, TJ=25℃
TA=125℃ for 1000 Hours
-30
VOSC=2.0V, TJ=25℃
TJ=25℃
0°C ≤ TA ≤ 70℃
VCC=12V ~ 25V
0°C ≤ TA ≤ 70℃
VOUT=2.5V
RL=15k to ground, VFB=2.3V
RL=15k to VREF, VFB=2.7V
VOUT=1.1V, VFB=2.7V
VOUT=5.0V, VFB=2.3V
VFB=2.7V
VOUT=2.0V ~ 4.0V
VCC=12V ~ 25V
TJ=25℃
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
4.9
TYP
47
46
50
5
-85
1.6
10.8
52
0.2
5.0
2.42
5.0
2.0
-0.5
65
60
0.7
2.50
6.2
0.8
12
-1.0
-0.1
90
70
1.0
V
mA
57
60
1.0
2.58
1.1
kHz
%
%
V
V
mA
-2.0
μA
dB
dB
MHz
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LINEAR INTEGRATED CIRCUIT
ELECTRICAL CHARACTERISTICS(Cont.)
PARAMETER
CURRENT SENSE SECTION
Current Sense Input Voltage Gain
(Note 2, 3)
Maximum Current Sense Input
Threshold (Note 2)
Input Bias Current
Power Supply Rejection Ratio
Propagation Delay
OUTPUT SECTION
SYMBOL
MIN
TYP
MAX
UNIT
GV
2.85
3.0
3.15
V/V
VI(THR)
0.9
1.0
1.1
V
-2.0
70
150
-10
μA
dB
ns
II(BIAS)
PSRR
TEST CONDITIONS
VCC=12V ~ 25V (Note4)
tPLH(IN/OUT)
Low
VOL
High
VOH
Output Voltage
ISINK=20mA
ISINK=200mA
ISINK=20mA
ISINK=200mA
VCC=6.0V, ISINK=1.0mA
CL=1.0nF,TJ=25°C
CL=1.0nF,TJ=25°C
13
12
0.1
1.6
13.5
13.4
0.1
50
50
300
0.4
2.2
V
V
Output Voltage with UVLO Activated
VOL(UVLO)
1.1
V
Output Voltage Rise Time
tR
150
ns
Output Voltage Fall Time
tF
150
ns
UNDERVOLTAGE LOCKOUT SECTION
UC3844
14.5
16.0
17.5
Startup Threshold
VTHR
V
UC3845
7.8
8.4
9.0
UC3844
8.5
10.0
11.5
Minimum Operating
VCC(MIN)
V
Voltage After Turn-On
UC3845
7.0
7.6
8.2
PWM SECTION
47
48
50
%
Max
DCMAX
Duty Cycle
Min
DCMIN
0
%
TOTAL DEVICE
Power Supply Zener Voltage
VZ
ICC=25mA
30
36
V
UC3845
0.5
1.0
VCC=6.5V
Power Supply Current
ICC
mA
(Note 4)
UC3844
VCC=14V
12
17
Startup Current
ISTART-UP VCC=14V, UVLO Active
0.3
0.5
mA
Note: 1. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient
as possible.
2. This parameter is measured at the latch trip point with VFB=0V.
3. Comparator gain is defined as:
ΔV Output Compensation
AV=
ΔV Current Sense Input
4. Adjust VCC above the startup threshold before setting to 15V.
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LINEAR INTEGRATED CIRCUIT
TYPICAL CHARACTERISTICS
„
Current Sense Input Threshold vs. Error Amp
Output Voltage
0
VCC = 15V
VOUT = 2.0V ~ 4.0V
RL = 100k
TA = 25℃
80
Gain
30
60
60
40
90
Phase
20
120
0
150
-20
10
100
1.0k
10k
100k
1.0M
Excess Phase Degrees, φ
Open Loop Voltage Gain, GV (dB)
100
180
10M
Frequency, f (Hz)
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Current Sense Input Threshold, VIN(THR) (V)
Error Amp Open Loop Gain Phase vs. Frequency
1.2
1.0
TA = 125℃
0.8
TA = 25℃
0.6
0.4
TA = -55℃
0.2
0
VCC = 15V
0
2.0
4.0
6.0
8.0
Error Amp Output Voltage, VOUT (V)
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UCX844
Supply Current, ICC (mA)
UCX845
TYPICAL CHARACTERISTICS(Cont.)
Output Saturation Voltage, VO(SAT) (V)
„
LINEAR INTEGRATED CIRCUIT
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
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