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UNISONIC TECHNOLOGIES CO., LTD U3525
REGULATING PWM IC
DESCRIPTION
The UTC U3525 is a pulse width modulator IC and designed for switching power supplies application to improve performance and reduce external parts usage. A shutdown terminal controls both the soft-start circuitry and the output stages, providing instantaneous turn off through the PWM latch with pulsed shutdown, as well as soft-start recycle with longer shutdown commands. The output stage features NOR logic, giving a LOW output for an OFF state. An under-voltage lockout circuitry, which keeps the outputs off and the soft-start capacitor discharged for sub-normal input voltages, includes approximately 500 mV of hysteresis for jitter free operation. The PWM circuits also feature a latch following the comparator. When a PWM pulses has been terminated, the outputs will remain off for the duration of the period. The latch is reset with each clock pulse. The output stages are totem-pole designs capable of sourcing or sinking in excess of 200mA.
LINEAR INTEGRATED CIRCUIT
SOP-16
DIP 16 -
*Pb-free plating product number: U3525L
FEATURES
* Input Voltage: 8~35V * On-chip +5.1V reference is trimmed to 1% * 100HZ ~ 500KHZ oscillator range * Separate oscillator sync terminal * Adjustable dead time control * Internal soft-start * Pulse-by-pulse shutdown * Input under-voltage lockout with hysteresis * Latching PWM to prevent multiple pulses * Dual source/sink output drivers
ORDERING INFORMATION
Normal U3525-D16-T U3525-S16-R U3525-S16-T Order Number Lead Free Plating U3525L-D16-T U3525L-S16-R U3525L-S16-T Package DIP-16 SOP-16 SOP-16 Packing Tube Tape Reel Tube
U3525L-D16-T (1)Packing Type (2)Package Type (3)Lead Plating (1) R: Tape Reel, T: Tube (2) D16: DIP-16, S16: SOP-16 (3) L: Lead Free Plating Blank: Pb/Sn ,
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QW-R103-032,A
U3525
PIN CONNECTIONS (top view)
LINEAR INTEGRATED CIRCUIT
INV.INPUT N.I.INPUT SYNC OSC.OUTPUT CT RT DISCHARGE SOFT-START
1 2 3 4 5 6 7 8
16 15 14 13 12 11 10 9
VREF +VI OUTPUT B VC GROUND OUTPUT A SHUT DOWN COMP
THERMAL DATA
SYMBOL RATING UNIT DIP16 JA 80 C/W Thermal Resistance Junction-ambient SOP-16 JA 50 C/W Note:Thermal resistance junction-alumina with the device soldered on the middle of an alumina supporting substrate measuring 15x20 mm; 0.65 mm thickness with infinite heat sink. PARAMETER
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QW-R103-032,A
U3525
BLOCK DIAGRAM
LINEAR INTEGRATED CIRCUIT
3 13
OSCI LLATOR
6 7 5
A
11
9 8 1 2 10 5k
-
PWM
B
14
EA
+
50A 12
5k 15 VREF 16 4 FLIP/ FLOP
UNISONIC TECHNOLOGIES CO., LTD
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QW-R103-032,A
U3525
ABSOLUATE MAXIUM RATINGS
LINEAR INTEGRATED CIRCUIT
PARAMETER SYMBOL RATINGS UNIT Supply Voltage ViN 40 V Collector Supply Voltage VC 40 V Oscillator Charging Current IOSC 5 mA Output Current, Source or Sink Io 500 mA Reference Output Current IR 50 mA mA Current through CT Terminal 5 V Logic Inputs IT - 0.3 ~ + 5.5 V Analog Inputs -0.3 ~ Vi Total Power Dissipation at Ta=70 C PD 1000 mW Junction Temperature TJ -55 ~ +125 Operating Ambient Temperature TORP 0 ~ +70 Storage Temperature TSTG -65 ~ +150 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.
RECOMMENDED OPERATING CONDITIONS (Note)
PARAMETER SYMBOL RATINGS Input Voltage VIN 8 ~ 35 Collector Supply Voltage VC 4.5 ~ 35 Sink/Source Load Current (steady state) ISTEAD 0 ~ 100 Sink/Source Load Current (peak) IPEAK 0 ~ 400 Reference Load Current ILOAD 0 ~ 20 Oscillator Frequency Range FO 100 ~ 400K Oscillator Timing Resistor RO 2 ~ 150 Oscillator Timing Capacitor CO 0.001 ~ 0.1 Dead Time Resistor Range RT 0 ~ 500 Note: Range over which the device is functional and parameter limits are guaranteed. UNIT V V mA mA mA Hz K F
ELECTRICAL CHARACTERISTICS(VIN= 25V, unless otherwise specified)
PARAMETER REFERENCE SECTION Output Voltage Total Output Variation (Note 1) Long Term Stability (Note 1) Line Regulation Load Regulation Temp. Stability (Note 1) Output Noise Voltage (Note 1) Short Circuit Current OSCILLATOR SECTION Clock Amplitude (Note 1, 2) Sync Threshold Sync Input Current Current Mirror Maximum Frequency Minimum Frequency Clock Width (Note 1, 2) Initial Accuracy (Note 1, 2) Voltage Stability (Note 1, 2) Temperature Stability (Note 1) SYMBOL VREF TEST CONDITIONS MIN 5 4.95 TYP 5.1 20 10 20 20 40 80 3 1.2 Sync Voltage = 3.5 V IRT = 2 mA RT = 2 K, CT = 470 pF RT = 200K, CT = 0.1F TJ = 25 TJ = 25 VIN = 8 ~ 35 V Over Operating Range 1.7 400 0.3 3.5 2 1 2 MAX UNIT
TJ= 25 Line, Load and Temperature VREF TJ= 125, 1000 hrs VREF VIN= 8 ~ 35 V VREF IL = 0 ~ 20 mA VREF/T Over Operating Range 10 Hz f 10 kHz, TJ = 25 VREF = 0, TJ = 25
5.2 V 5.25 V 50 mV 20 mV 50 mV 50 mV 200 Vrms 100 mA V V mA mA KHz Hz s % % % 4 of 9
QW-R103-032,A
2.8 2.5 2.2 120 1 6 2 6
fMAX fMIN
f/T
0.5 2 1 3
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U3525
ELECTRICAL CHARACTERISTICS(Cont.)
PARAMETER SYMBOL ERROR AMPLIFIER SECTION (VCM = 5.1 V) Output Low Level Output High Level Input Offset Voltage VOS Input Bias Current Ib Input Offset Current Ios Comm. Mode Reject. CMR Supply Voltage Rejection PSR DC Open Loop Gain DC Transconduct. (Note 1, 3) Gain Bandwidth Product (Note 1) PWM COMPARATOR Input Threshold (Note 2) Input Bias Current (Note 1) Minimum Duty-cycle Maximum Duty-cycle (Note 2) SHUTDOWN SECTION Soft Start Low Level Shutdown Threshold Shutdown Input Current Soft Start Current Shutdown Delay (Note 1) OUTPUT DRIVERS (each output) (VC = 20 V) Output Low Level Output High Level
LINEAR INTEGRATED CIRCUIT
TEST CONDITIONS
MIN
TYP 0.2 5.6 2 1 75 60 75 1.5 2 0.9 3.3 0.05 49 0.4 0.8 0.4 50 0.2 0.2 1 19 18 7
MAX UNIT 0.5 10 10 1 V V mV A A dB dB dB ms MHz V V A % % V V mA A s V V V V V A ns ns
3.8
VCM = 1.5 ~ 5.2 V VIN = 8 ~ 35 V RL 10 M 30 K RL1 M, TJ = 25 Gv = 0 dB, TJ = 25 Zero Duty-cycle Maximum Duty-cycle
60 50 60 1.1 1 0.7
3.6 1 0
45 VSD = 2.5 V To outputs, VSS = 5.1 V, TJ = 25 VSD = 2.5 V VSD = 0 V, VSS = 0 V VSD = 2.5 V, TJ = 25 ISINK = 20 mA ISINK = 100 mA ISOURCE = 20 mA ISOURCE = 100 mA VCOMP and VSS = High VC = 35 V CL = 1 nF, TJ = 25 C CL = 1 nF, TJ = 25 C
0.6 25
0.7 1 1 80 0.5 0.4 2
Under-Voltage Lockout 8 Collector Leakage IC 200 Rise Time (Note 1) tR 100 600 Fall Time (Note 1) tF 50 300 TOTAL STANDBY CURRENT Supply Current IS VIN = 35 V 14 20 mA Note:1.The parameters are not 100% tested in production. 2.Tested at fosc=40 KHz (RT=3.6 K, CT=10nF, RD=0 ). Approximate oscillator frequency is defined by : 1 f= C T(0.7R T + 3R D) 3.DC transconductance (gM) relates to DC open-loop voltage gain (GV) according to the following equation: GV=gM RL where RL is the resistance from pin 9 to ground. The minimum gM specification is used to calculate minimum GV when the error amplifier output is loaded.
18 17 6
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5 of 9
QW-R103-032,A
U3525
TEST CIRCUIT
VREF
LINEAR INTEGRATED CIRCUIT
15
+V1 0.1F
16
0.1F CLOCK 3k SYNC RT PWM ADJ. 10k 3.6k 6 DEAD TIME 7 9nF RAMP 100 5 CT 0.1F 1nF 10k COMP 9 1 2 3 21 3 0.01F 1 12 3 11 4 13
VC 0.1F OUTA 1K 1W 1K
UTC U3525
1W 14 OUT B
1.5k
GND
SOFT START 8 5F 10 2k VREF SHUT DOWN
2 3 V/I METER VOS = 1 (+) = 2 (-) = 3 1 2 3
2
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APPLICATION INFORMATION AND CIRCUIT
LINEAR INTEGRATED CIRCUIT
SHUTDOWN OPTIONS (see Block Diagram) Since both the compensation and soft-start terminals (Pins 9 and 8) have current source pull-ups, either can readily accept a pull-down signal which only has to sink a maximum of 100A to turn off the outputs. This is subject to the added requirement of discharging whatever external capacitance may be attached to these pins. An alternate approach is the use of the shutdown circuitry of Pin 10 which has been improved to enhance the available shutdown options. Activating this circuit by applying a positive signal on Pin 10 performs two functions: the PWM latch is immediately set providing the fastest turn-off signal to the outputs; and a 150A current sink begins to discharge the external soft-start capacitor. If the shutdown command is short, the PWM signal is terminated without significant discharge of the soft-start capacitor, thus, allowing, for example, a convenient implementation of pulse-by-pulse current limiting. Holding Pin 10 high for a longer duration, however, will ultimately discharge this external capacitor, recycling slow turn-on upon release. Pin 10 should not be left floating as noise pickup could conceivably interrupt normal operation. OSCILLATOR SCHEMATIC
VREF 15 Q1 Q2 Q4 Q6 Q5 7.4K
RT 6 CT 5
Q3
Q7
Q8
Q9 2k SYNC.
3
TO PWM COMPARATOR
14K
DISCHARGE 7
Q17 400A 2k Q10 Q11 Q14 1K GND Q12 Q13 Q15 23K 1K Q16 3K 250 4 CLOCK 25K 5pF BLANKING TO OUTPUT
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www.unisonic.com.tw
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QW-R103-032,A
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OUTPUT CIRCUIT (1/2 CIRCUIT SHOWN)
LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION AND CIRCUIT(Cont.)
+VI Q5 Q7 Q4 Q6 Q10
13 +VC
Q11 5K 11 OUTPUT Q8 Q9 Q12 2K 14
+VREF
Q3
Q3
Q3
5K
10K
10K
CLOCK
F/F
PWM
ERROR AMPLIFIER
+VI 15 Q3
Q4
9
COMP.
Q5 INV INPUT N. I. INPUT 1 Q1 Q2
100
2 200A 100A 5.8V
TO PWM COMPARATOR
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www.unisonic.com.tw
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QW-R103-032,A
U3525
TYPICAL CHARACTERISTICS
Oscillator Charge Time vs. RT and CT 400 50 20 10 5 2 1 2 5 10 20 50 100 2005001ms2ms T (s)
CT = CT= 1nF 2n C C T =5n F C T =10n F T= 20 F C n T= 50 F CT nF =0 .1 F
LINEAR INTEGRATED CIRCUIT
Oscillator DisCharge Time vs. R D and CT
300
RD ()
RT (K)
RD=0
200
6
5
RT
RD7 CT
100 0 0.5 1 2 5 10 20 T (s) 50
Output Saturation Characteristics
Error Amplifier Voltage Gain and Phase vs Frequency . 80 R L= 1M 60 300k 100k 40 30k Values below 30k 20 will begin to limit the maximum duty cycle 0 PHASE 100 1k 10k 100k 1M -180 -270 -360 VIN=20V
VIN=20V Tamb=25 2
SOURCE SAT,VC-VOH SINK SAT, VOL
1
0 0.01
0.1 IOUT (A)
f (Hz)
UTC assumes no responsibility for equipm ent failures that result from using products at values that exceed, even mom entarily, rated values (such as m aximum ratings, operating condition ranges, or other param eters) 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 system s where m alfunction 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 inform ation presented in this docum ent does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.
UNISONIC TECHNOLOGIES CO., LTD
www.unisonic.com.tw
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QW-R103-032,A
Open Loop Phase
G V (dB)
3
VCE (V)
CT=1 nF CT=2 nF CT= 5nF CT= 1 0n F CT = 20 n F CT= 1 0n F CT = 0.1 F

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