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UNISONIC TECHNOLOGIES CO., LTD U3848/A/B/C
HIGH PERFORMANCE CURRENT MODE PWM CONTROLLERS
DESCRIPTION
The UTC U3848/A/B/C is designed to provide several special enhancements to satisfy the needs: Power-Saving mode for low standby power, Over Current Protection (OCP), Over Voltage Protection (OVP), Over Load Protection (OLP), Over Temperature Protection (OTP) etc protection features. IC will be shutdown when either protection arise and can auto-restart. Its frequency may be defined by user through resistor RT to external ground. UVLO featuring typical start-up current 20A, and VCC(ON) 12.6V, VCC(OFF) 8.1 . Lower typical operation current Icc 3.7mA at inactive output. The output stage, suitable for driving N-Channel MOSFETs, can operate to duty cycles approach 70%. The U3848/A/B/C are fully pin-to-pin compatible with UC3842. But pin RT only connected a resistor to ground to decide switch frequency, and pin FB with an 4k pull up resistor to internal reference voltage. The U3848/A/B/C also have soft-start function avoiding overshoot, and controlled driver output rise edge time tR for low EMI.
LINEAR INTEGRATED CIRCUIT
DIP-8
SOP -8
*Pb-free plating product number: U3848L/U3848AL/U3848BL/U3848CL
FEATURES
* Low startup and operation current * User defined switching frequency(Norm is 70kHz) * Max duty cycle 70% * Power-saving mode for low power * Under voltage lockout with hysteresis * Over temperature protection * Overload protection * Over voltage protection * Leading edge blanking * Soft start
ORDERING INFORMATION
Order Number Normal Lead Free Plating U3848-D08-T U3848L-D08-T U3848-S08-R U3848L-S08-R U3848-S08-T U3848L-S08-T U3848A-D08-T U3848AL-D08-T U3848A-S08-R U3848AL-S08-R U3848A-S08-T U3848AL-S08-T U3848B-D08-T U3848BL-D08-T U3848B-S08-R U3848BL-S08-R U3848B-S08-T U3848BL-S08-T U3848C-D08-T U3848CL-D08-T U3848C-S08-R U3848CL-S08-R U3848C-S08-T U3848CL-S08-T www.unisonic.com.tw Copyright (c) 2005 Unisonic Technologies Co., Ltd Package DIP-8 SOP-8 SOP-8 DIP-8 SOP-8 SOP-8 DIP-8 SOP-8 SOP-8 DIP-8 SOP-8 SOP-8 Packing Tube Tape Reel Tube Tube Tape Reel Tube Tube Tape Reel Tube Tube Tape Reel Tube 1 of 13
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U3848/A/B/C
ORDERING INFORMATION(Cont.)
U3848L-D08-T (1)Packing Type (2)Package Type (3)Lead Plating
LINEAR INTEGRATED CIRCUIT
(1) R: Tape Reel, T: Tube (2) D08: DIP-8, S08: SOP-8 (3) L: Lead Free Plating, Blank: Pb/Sn
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U3848/A/B/C
PIN CONFIGURATION
LINEAR INTEGRATED CIRCUIT
SS 1
8 VREF
FB 2
7 VCC
CS 3
6 OUT
RT 4
5 GND
PIN DESCRIPTION
PIN 1 2 3 4 5 6 7 8 SYMBOL SS FB CS RT GND OUT VCC VREF FUNCTION Soft-start Feedback Controller current sense input The resistor controlling switch frequency Ground Output to the gate of external power MOS Supply voltage Inter 6.3V reference voltage, connected with the filter capacitor
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U3848/A/B/C
BLOCK DIAGRAM
LINEAR INTEGRATED CIRCUIT
VCC 7
VREF 8
RT 4
OVP OLP OTP
UVLO Reference voltage
Oscillator
SS
1
Soft Start
Latch SQ
Power-Saving Unit
Driver 6 OUT
R
Q
FB
2
PWM COMP
Current Limiting
LEB
3
CS
5 GND
Explain:OLP(Over Load Protection) OVP(Over Voltage Protection) OTP(Over Temperature Protection) UVLO(Under Voltage Latch-Out LEB(Led Edge Blanking) SS(Soft Start)
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U3848/A/B/C
PARAMETER
LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATINGS (Ta 25C, VCC=15V, RT=75k, unless otherwise specified)
SYMBOL RATINGS UNIT Supply Voltage VCC 26 V Input Voltage to FB Pin VFB -0.3 ~ 6.2 V Input Voltage to CS Pin VCS -0.3 ~ 2.8 V Input Voltage to RT Pin VRT -0.3 ~ 6.2 V Junction Temperature TJ +150 C Operating Temperature TOPR -40 ~ +125 C Storage Temperature TSTG -50 ~ +150 C Note 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.
OPERATING RANGE
PARAMETER Supply Voltage SYMBOL VCC RATINGS 8.2 ~ 21 UNIT V
ELECTRICAL CHARACTERISTICS (Ta 25C, VCC=15V, RT=75k, unless otherwise specified)
PARAMETER SUPPLY SECTION Start Up Current SYMBOL TEST CONDITIONS VCC=12.5V VSS = 0, IFB = 0 VSS = 5V, IFB = 0 11.8 7.6 MIN TYP 27 3.7 4.0 12.6 8.1 4.5 6.3 95 68 20 70 MAX 45 5.5 6.0 13.4 8.6 UNIT A mA mA V V V V kHz kHz kHz % % V V k k ms ms ms 16.8 4.9 150 4.2 5.4 V V C V V s ns
ISTR OFF IOFF Supply Current with switch ON ION UNDER-VOLTAGE LOCKOUT SECTION Start Threshold Voltage VTHD(ON) Min. Operating Voltage VCC(MIN) Hysteresis VCC(HY) INTERNAL VOLTAGE REFERENCE Reference Voltage VREF CONTROL SECTION Switch Frequency Duty Cycle VFB Operating Level Normal Power-Saving MAX MIN MIN MAX F(SW) DMAX DMIN VMIN VMAX RFB RT
measured at pin VREF VFB = 4V VFB = 1V VFB < 0.5V U3848/B(Note1) U3848A/C(Note2)
6.1 85 61 17 65 0 0.5 2.6
6.6 105 75 23 75
Feedback Resistor External Resistor for controlling Current Source of OSC Soft-Start Time PROTECTION SECTION OVP threshold OLP threshold OTP threshold OVP Disable threshold OLP Enable threshold Spike Blanking time CURRENT LIMITING SECTION LEB
3.8 75
4.4 5.0
CSS=0.05uF TSS CSS=0.1uF CSS=1uF VSS < 3.5V, VFB > 5V VSS > 5.4V VFB > 5V, VCC > 17V VFB > 5V 15.2 4.4 120 3.7 4.9
6 12 120 16 4.6 135 3.9 5.1 7.2 220
V(OVP) VFB(OLP) T(THR) VSS(DEACT) VSS(ACT) TSB tLEB
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U3848/A/B/C
ELECTRICAL CHARACTERISTICS(Cont.)
PARAMETER DRIVER OUTPUT SECTION Output Voltage Low State Output Voltage High State SYMBOL VOL VOH
LINEAR INTEGRATED CIRCUIT
TEST CONDITIONS
MIN
TYP
MAX 2.5
UNIT V V ns ns ns ns
ISOURCE = 200 mA ISINK = 200 mA U3848B CL = 1.0 nF Output Voltage Rise Time tR U3848C CL = 1.0 nF U3848/A CL = 1.0 nF Output Voltage Fall Time tF CL = 1.0 nF Note: 1. RT=65k should be connected for U3848/ U3848B. 2. U3848A/C denote U3848A and U3848C.
12.2 70 200 300 50 150 300 400 90
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U3848/A/B/C
FUNCTIONAL DESCRIPTION
LINEAR INTEGRATED CIRCUIT
The internal reference voltages and bias circuit work at VCC>12.6V, and shutdown at VCC< 8.1V. (1) Soft-Start When every IC power on, driver output duty cycle will be decided by voltage VSS on soft-start capacitor and VCS on current sense resistor at beginning. After VSS reach 5.1V, the whole soft-start phase end, and driver duty cycle depend on VFB and VCS. The relation among VSS, VFB and VOUT as followed FIG.3, here soft-start phase Tsoft-start should more than VOUT start-up phase Tstart-up, otherwise, IC will enter false OLP protection state. Because after the soft-start phase end, if VOUT remain in lower voltage, VFB more than 4.6V, then IC enter false OLP state. Furthermore, soft-start phase should end before VCC reach VCC(MIN) during VCC power on. Otherwise, if soft-start phase remain not end before VCC reach VCC(MIN) during VCC power on, IC will enter auto-restart phase and not set up VOUT. Finally soft-start also set OVP active phase. OVP active phase between VSS=0 and VSS=3.8V, OVP will not be sensed after VSS reach 3.8V.The Soft-start phase TSS 6 ms 12 ms 120 ms (CSS=0.05uF) (CSS=0.1uF) (CSS=1uF)
TSS =
VSS
5.1V
TSOFT-START t VFB
4.6V
t VOUT
TSTRAT-UP t Driver
t
FIG.3 Soft-start phase
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U3848/A/B/C
FUNCTIONAL DESCRIPTION(Cont.)
LINEAR INTEGRATED CIRCUIT
(2) Switch Frequency Set The maximum switch frequency decided by an external resistor RT connected between pin RT and ground. Then the maximum switch frequency will depend on user requirement. The relation curve between fSW and RT as followed FIG.5 under the condition of POUT=8W. The equation between fSW and RT as followed (1-2) for U3848A/C, (1-3) for U3848/B: fSW = -0.61*RT+115.7--------------------------(1-2) fSW = -1.1*RT+167.5--------------------------(1-3) After RT connected, switch frequency is also modulated by output power POUT during IC operating. So lower switch frequency at lower load, which more and more improve IC's efficiency at light load. Switch frequency is decreased minimum at no load, then the U3848/B will operate at Power-Saving mode for Lower standby power. The relation curve between fSW and POUT as followed FIG.4 under the condition of RT=75k. The frequency wave of U3848A/C is similar with U3848/B's, and for them, maximum frequency point is 70kHz.
90 80 70 60 110V 220V
fsw (kHz)
50 40 30 20 10 0 0.6 1.2 1.8 2.4 3
3.6 4.8
6
7.2 12
POUT(W) (RT=75K)
FIG.4 The relation curve between fSW and output power POUT
100 90 80 70
fsw (kHz)
60 50 40 30 20 10 55 60 65 70 75 80 85 90 95
RT (k ) (POUT=8W)
FIG.5 The relation curve between fSW and RT
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U3848/A/B/C
FUNCTIONAL DESCRIPTION(Cont.)
LINEAR INTEGRATED CIRCUIT
(3) Protection section U3848/A/B/C takes on more protection functions such as OLP, OVP and OTP etc. In case of those failure modes for continual 7.2s (blanking time), the driver is shut down. At the same time, IC enters auto-restart, VCC power on and driver is reset after VCC power on again. OLP After soft-start phase end (VSS>5.1V), IC will shutdown driver if over load state occurs (corresponding to VFB>4.6V) for continual 7.2s. OLP function will not inactive during soft-start phase. OLP case as followed FIG.6. The test circuit as followed FIG.8 for U3848/A/B/C.
VCC
12.6V 8.1V
VCC
16V 12.6V 8.1V T restart
VOUT
t
Driver ON/OFF
t
VFB
4.6V
t
7.2s Blanking 7.2s Blanking
VFB
4.6V
t
7.2s Blanking 7.2s Blanking
VSS
5.1V
t
VSS
5.1V 3.9V
SS Phase
t
SS Phase
OVP Phase
t
FIG.6 OLP case FIG.7 OVP case
t
OVP Power supply VCC's OVP function are enabled only when VSS<3.9V & VFB>4.6V during soft-start phase. During above condition, driver will be shutdown if over voltage state occurs (VCC>16V) for continual 7.2s. OVP function will not inactive after soft-start phase. OLP case as followed FIG.7. The test circuit as followed FIG.9 for U3848/A/B/C. OTP OTP will shut down driver when junction temperature TJ of internal circuits is more than threshold 135C for continual 7.2s.
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U3848/A/B/C
FUNCTIONAL DESCRIPTION(Cont.)
15V VCC
LINEAR INTEGRATED CIRCUIT
VCC
C4
C13 5.5V
IC3
1 2 UTC U3848/A/B/C 3 6 8 7
C4 C3
C13
IC3
1 8 7 UTC U3848 /A/B/C 3 6
C3
Driver VFB 3.5V
2
Driver
V FB
4
5 4.6v VFB RT
4
5 16v VCC
(4) Driver Output Section Rise edge time of driver output is about 200ns for avoiding Low EMI. When driver output VOL(MAX) is less than 2.5V with 200mA source current, and VOH(MIN) is more than 12.2V with 200mA sink current.
R17
7.2us
R17
RT
7.2us
FIG.8 OLP test circuit
FIG.9 OVP test circuit
15v
VCC
15v
VCC
C4
C13
IC3
1 2 8 7 UTC U3848 A/ B/C 3 6
C4 C3
C13
IC3
1 2 8 7 UTC U3848 /A/B/C 3 6
C3
Isource=200mA VOL (MIN)
VFB
VOH
VFB
(MIN )
4
5 Isink=200mA
4
5
R17
RT
R17
RT
FIG.10 driver test circuit with sink current
FIG.11 driver test circuit with source current
(5) External power switch MOS transistor Because U3848/A/B/C driver output voltage Low level threshold is about 2.5V, User may apply power MOS transistors with bigger threshold. 4N60 is recommended normally.
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U3848/A/B/C
TYPICAL APPLICATION CIRCUIT
BD1 AC IN CX1 TH1 F1
LINEAR INTEGRATED CIRCUIT
D3 C8 TR1
D1 CD1 RD1 + C5
L3
R12
+
5V 3A
ZD1
+ C9
R10
C12
D2 Q1
R7 4 3 C15 1
IC3
UTC A/B/C
R6
5 6 8 R
GND
R5 R4 R3
R8
2 U3848 / 7
R2 IC1 RF R17 C2
R11
C14
C3
+ C4
IC2
CY1
FIG.12 U3848/A/B/C Typical Application Circuit
Table1 Components Reference description for U3848/A/B/C application circuit C12 C14 C2 CX1 C5 C4 C8 C9 CD1 CY1 D1 D2 EC CC EC EC CC CC Diode Diode CC CC CC 10nF/1000V 100nF/50V 33nF/50V 104/275V 1000uF/15V 22uF/50V 68uF/400V 1000uF/16V 1nF/1KV 4.7nF/250V C63-004 1N4148 D3 IC1 IC2 IC3 L3 Q1 R7 R17 R2 R3 R4 R5 Diode IC IC IC L MOS R R R R R R UF1007 PC817 TL431CLP U3848/A/B/C 1.2uH 4N60 68K 1.2/1W 680 ADJ 5.6K 5.6K 1/8W 1/8W 1/8W 1/8W 1/8W 1/8W R TH1 BD1 RD1 R12 TR1 RF C15 R CC R R R R 470K SCK-103 KBP-208 10 3.3k optional 4.7k 0.1F/50V 1/8W 1/8W 1/8W 1/8W
Note: C5 and C9 are lower ESR capacitors.
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U3848/A/B/C
TYPICAL CHARACTERISTICS(Cont.)
LINEAR INTEGRATED CIRCUIT
Feedback Voltage During Loadjump From10% Up To 100% Load (VDCIN=120V)
120mV 3.86V 1.64kHz 850 Hz
Feedback Voltage During Loadjump From10% Up To 100% Load (VDCIN=350V)
60.0 mV 3.30 V 3.29kHz 1.70kHz
Ch1 max 6.00V Ch1 min 460 mV Ch1 frequency 785 .5 Hz
Ch1 max 5.90V Ch1 min 40.0mV Ch1 frequency 1.906kHz
Ch1
1.00V
M 400
s A Ch1
3.18V
Ch1
1.00 V
M 200
s A Ch1
2.68 V
Startup With Full Load Condition At V =120V, DCIN Vc4 and Vout
12.3V 12.3V
Startup With Full Load Condition At V =350V, DCIN Vc4 and Vout
12.3V 12.3V
VC4
VC4
Ch1 max 5.04V
Ch1 max 5.04V
Ch1 min 1.32V Ch1 frequency ----- Hz
Ch1 min -120 mV Ch1 frequency ----- Hz
VOUT
VOUT
Ch1
2.00V
Ch2
5.00V
M 10.0ms A
Ch1
3.16V
Ch1
2.00V
Ch2
5.00V
M 10.0ms A
Ch1
3.16V
Startup Behavior At Nominal Load Condition VDCIN =120 V 120mV 12.3V 357Hz 21.2Hz
Startup Behavior At Nominal Load Condition VDCIN =350 V 240 mV 12.0V 1.79kHz 147 Hz
VC4
VC4
VFB VSS
VFB V SS
Ch1 Ch3
2.00V 2.00V
Ch2
2.00V
M 4 .00 ms A
Ch3
4 .96 V
Ch1 Ch3
2.00 V 2.00 V
Ch2
2.00V
M 4.00ms A
Ch3
4.96V
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TYPICAL CHARACTERISTICS(Cont.)
LINEAR INTEGRATED CIRCUIT
Frequency vs. Output Power 120 100 1 0.9 0.8
NO Load Input Power vs. Line Voltage (Normal Mode)
Input Power (W)
Frequency (KHZ)
80 60 40 20 0 0 2 4 6 8 10 12 14 16 18 20
Vdcin=120V
0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 100 150
Input Power NO Load (PoUT=0W)
200
250
300
Output Power (W)
DC Input Voltage(V)
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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