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FEATURES
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LT1070/LT1071 5A and 2.5A High Efficiency Switching Regulators DESCRIPTION
The LT (R)1070/LT1071 are monolithic high power switching regulators. They can be operated in all standard switching configurations including buck, boost, flyback, forward, inverting and "Cuk". A high current, high efficiency switch is included on the die along with all oscillator, control and protection circuitry. Integration of all functions allows the LT1070/LT1071 to be built in a standard 5-pin TO-3 or T0-220 power package. This makes it extremely easy to use and provides "bust proof" operation similar to that obtained with 3-pin linear regulators. The LT1070/LT1071 operate with supply voltages from 3V to 60V, and draw only 6mA quiescent current. They can deliver load power up to 100W with no external power devices. By utilizing current mode switching techniques, they provide excellent AC and DC load and line regulation. The LT1070/LT1071 have many unique features not found even on the vastly more difficult to use low power control chips presently available. They use adaptive antisat switch drive to allow very wide ranging load currents with no loss in efficiency. An externally activated shutdown mode reduces total supply current to 50A typical for standby operation. Totally isolated and regulated outputs can be generated by using the optional "flyback regulation mode" built into the LT1070/LT1071, without the need for optocouplers or extra transformer windings.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Wide Input Voltage Range: 3V to 60V Low Quiescent Current: 6mA Internal 5A Switch (2.5A for LT1071) Very Few External Parts Required Self Protected Against Overloads Operates in Nearly All Switching Topologies Shutdown Mode Draws Only 50A Supply Current Flyback Regulated Mode Has Fully Floating Outputs Comes in Standard 5-Pin Packages Can be Externally Synchronized (Consult Factory)
APPLICATIONS
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Logic Supply 5V at 10A 5V Logic to 15V Op Amp Supply Off-Line Converter Up to 200W Battery Upconverter Power Inverter (+ to -) or (- to +) Fully Floating Multiple Outputs For Lower Current Applications, See the LT1072
USER NOTE: This data sheet is only intended to provide specifications, graphs and a general functional description of the LT1070/LT1071. Application circuits are included to show the capability of the LT1070/LT1071. A complete design manual (AN19) should be obtained to assist in developing new designs. This manual contains a comprehensive discussion of both the LT1070 and the external components used with it, as well as complete formulas for calculating the values of these components. The manual can also be used for the LT1071 by factoring in the lower switch current rating. A second Application Note, AN25, which details off-line applications is available.
TYPICAL APPLICATION
Boost Converter (5V to 12V)
L2 10H 5V L1** 150H D1 VIN C3* 100F VSW OUTPUT FILTER C3 100F POWER (W)** 100 80
Maximum Output Power*
60
+
LT1070 GND VC FB R3 1k C1 1F *REQUIRED IF INPUT LEADS 2" **PULSE ENGINEERING 92113
+
12V 1A C2 1000F R1 10.7k 1%
40 ISOLATED 20 BUCK/BOOST VO = 5V 0 0 10 30 20 INPUT VOLTAGE (V) 40 50
1070/71 TA02
R2 1.24k 1%
1070/71 TA01
*ROUGH GUIDE ONLY. BUCK MODE POUT = 5A * VOUT. SPECIAL TOPOLOGIES DELIVER MORE POWER **DIVIDE VERTICAL POWER SCALE BY 2 FOR LT1071
U
U
U
BOOST BUCK/BOOST VO = 30V FLYBACK
1
LT1070/LT1071
ABSOLUTE MAXIMUM RATINGS
Supply Voltage LT1070/LT1071 (Note 2) .................................... 40V LT1070HV/LT1071HV (Note 2)........................... 60V Switch Output Voltage LT1070/LT1071 .................................................. 65V LT1070HV/LT1071HV......................................... 75V Feedback Pin Voltage (Transient, 1ms) ................ 15V
PACKAGE/ORDER INFORMATION
BOTTOM VIEW VSW 1 2 3 VC
ORDER PART NUMBER
CASE IS GND
4 VIN
FB K PACKAGE 4-LEAD TO-3 METAL CAN
TJMAX = 100C, JA = 35C/ W, QJC = 2C (LT1070C, I) TJMAX = 150C, JA = 35C/ W, QJC = 2C (LT1070M) TJMAX = 100C, JA = 35C/ W, QJC = 4C (LT1071C, I) TJMAX = 150C, JA = 35C/ W, QJC = 4C (LT1071M)
LT1070CK LT1070HVCK LT1070HVMK LT1070IK LT1070MK LT1071CK LT1071HVCK LT1071HVMK LT1071MK
ELECTRICAL CHARACTERISTICS
SYMBOL VREF IB gm PARAMETER Reference Voltage Feedback Input Current Error Amplifier Transconductance Error Amplifier Source or Sink Current Error Amplifier Clamp Voltage Reference Voltage Line Regulation AV IQ Error Amplifier Voltage Gain Minimum Input Voltage Supply Current Control Pin Threshold Normal/Flyback Threshold on Feedback Pin
VIN = 15V, VC = 0.5V, VFB = VREF, output pin open unless otherwise specified.
MIN
q
CONDITIONS Measured at Feedback Pin, VC = 0.8V VFB = VREF
q
IC = 25A
q
VC = 1.5V
q
Hi Clamp, VFB = 1V Lo Clamp, VFB = 1.5V 3V VIN VMAX, VC = 0.8V 0.9V VC 1.4V
q q
3V VIN VMAX, VC = 0.6V Duty Cycle = 0
q
2
U
U
W
WW
U
W
(Note 1)
Operating Junction Temperature Range Commercial (Operating) ....................... 0C to 100C Commercial (Short Circuit)................... 0C to 125C Industrial ......................................... - 40C to 125C Military ............................................ - 55C to 150C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec)................. 300C
ORDER PART NUMBER
FRONT VIEW 5 4 3 2 1 T PACKAGE 5-LEAD PLASTIC TO-220 VIN VSW GND FB VC
TJMAX = 100C, JA = 75C/ W, QJC = 2C (LT1070C, I) TJMAX = 100C, JA = 75C/ W, QJC = 4C (LT1071C)
LT1070CT LT1070HVCT LT1070HVIT LT1070IT LT1071CT LT1071HVCT LT1071HVIT LT1071IT
TYP 1.244 1.244 350
MAX 1.264 1.274 750 1100 6000 7000 350 400 2.30 0.52 0.03
UNITS V V nA nA mho mho A A V V %/V V/V V mA V V V
1.224 1.214
3000 2400 150 120 1.80 0.25 500
4400 200
0.38 800 2.6 6
3.0 9 1.08 1.25 0.54
0.8 0.6 0.4
0.9 0.45
LT1070/LT1071
ELECTRICAL CHARACTERISTICS
SYMBOL VFB PARAMETER Flyback Reference Voltage Change in Flyback Reference Voltage Flyback Reference Voltage Line Regulation Flyback Amplifier Transconductance (gm) Flyback Amplifier Source and Sink Current BV Output Switch Breakdown Voltage
VIN = 15V, VC = 0.5V, VFB = VREF, output pin open unless otherwise specified.
MIN
q
CONDITIONS IFB = 50A 0.05 IFB 1mA IFB = 50A, 3V VIN VMAX (Note 3) IC = 10A VC = 0.6V, IFB = 50A (Source) VC = 0.6V, IFB = 50A (Sink) 3V VIN VMAX, ISW = 1.5mA (LT1070/LT1071) (LT1070HV/LT1071HV) LT1070 LT1071 LT1070 LT1071 Duty Cycle 50%, TJ 25C Duty Cycle 50%, TJ < 25C Duty Cycle = 80% (Note 5) Duty Cycle 50%, TJ 25C Duty Cycle 50%, TJ < 25C Duty Cycle = 80% (Note 5)
q q q q q q q q q q q q
TYP 16.3 6.8 0.01 300 32 40 90 90 0.15 0.30 8 4
MAX 17.6 18.0 8.5 0.03 650 70 70
UNITS V V V %/V mho A A V V
15 14 4.5 150 15 25 65 75
VSAT
Output Switch "On" Resistance (Note 4) Control Voltage to Switch Current Transconductance
0.24 0.50
A/V A/V
ILIM
Switch Current Limit (LT1070)
5 5 4 2.5 2.5 2.0 25 35 33 90 40 92 1.5 100
10 11 10 5.0 5.5 5.0 35 45 47 97 250 250 300
A A A A A A mA/A kHz kHz % s A mV mV
Switch Current Limit (LT1071)
IIN ISW f DC (Max)
Supply Current Increase During Switch "On" Time Switching Frequency
q
Maximum Switch Duty Cycle Flyback Sense Delay Time Shutdown Mode Supply Current Shutdown Mode Threshold Voltage 3V VIN VMAX, VC = 0.05V 3V VIN VMAX
q
100 50
150
The q denotes the specifications which apply over the full operating temperature range. Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Minimum switch "on" time for the LT1070/LT1071 in current limit is 1s. This limits the maximum input voltage during short-circuit conditions, in the buck and inverting modes only, to 35V. Normal (unshorted) conditions are not affected. Mask changes are being implemented which will reduce minimum "on" time to 1s, increasing maximum short-circuit input voltage above 40V. If the present LT1070/LT1071 (contact factory for package date code) is being operated in the buck or inverting mode at high input voltages and short-circuit conditions are expected, a resistor must be placed in series with the inductor, as follows: The value of the resistor is given by:
R= t * f * VIN - VF - RL ILIMIT
t = Minimum "on" time of LT1070/LT1071 in current limit, 1s f = Operating frequency (40kHz) VF = Forward voltage of external catch diode at ILIMIT ILIMIT = Current limit of LT1070 ( 8A), LT1071 ( 4A) RL = Internal series resistance of inductor Note 3: VMAX = 55V for LT1070HV and LT1071HV to avoid switch breakdown. Note 4: Measured with VC in hi clamp, VFB = 0.8V. ISW = 4A for LT1070 and 2A for LT1071. Note 5: For duty cycles (DC) between 50% and 80%, minimum guaranteed switch current is given by ILIM = 3.33 (2 - DC) for the LT1070 and ILIM = 1.67 (2 - DC) for the LT1071.
3
LT1070/LT1071 TYPICAL PERFORMANCE CHARACTERISTICS
Switch Current Limit vs Duty Cycle
16 14
SWITCH CURRENT (A)
FOR LT1071, DIVIDE VERTICAL SCALE BY 2
12
TIME (s)
1070/71 G02
10 - 55C 8 6 4 2 0 0 10 20 30 40 50 60 70 80 90 100 DUTY CYCLE (%)
1070/71 G01
25C
DUTY CYCLE (%)
125C
Minimum Input Voltage
2.9 SWITCH SATURATION VOLTAGE (V) SWITCH CURRENT = 5A 2.8 2.7 2.6 SWITCH CURRENT = 0A 2.5 2.4 2.3 -75 - 50 - 25
MINIMUM INPUT VOLTAGE (V)
100C 1.0 0.8 0.6 0.4 0.2 0 0 1 4 5 2 3 6 SWITCH CURRENT (A) 7 8 25C - 55C
FLYBACK VOLTAGE (V)
0 25 50 75 100 125 150 TEMPERATURE (C)
1070/71 G04
Line Regulation
5 REFERENCE VOLTAGE CHANGE (mV) 4 REFERENCE VOLTAGE (V) 3 2 1 0 -1 -2 -3 -4 -5 0 10 30 40 20 INPUT VOLTAGE (V) 50 60 TJ = - 55C TJ = 150C TJ = 25C
1.246 1.244 1.242 1.240 1.238 1.236 1.234 - 75 - 50 - 25
40 39
FEEDBACK BIAS CURRENT (nA)
4
UW
1070/71 G07
Maximum Duty Cycle
96 95 94 93 92 91 90 -75 - 50 - 25 0 25 50 75 100 125 150 JUNCTION TEMPERATURE (C) 2.2 2.0 1.8 1.6 1.4 1.2
Flyback Blanking Time
1.0 -75 - 50 - 25 0 25 50 75 100 125 150 JUNCTION TEMPERATURE (C)
1070/71 G03
Switch Saturation Voltage
1.6 1.4 1.2 FOR LT1071, DIVIDE CURRENT BY 2 150C 21 20 19 18 17 16 23 22
Isolated Mode Flyback Reference Voltage
RFEEDBACK = 500
RFEEDBACK = 1k
RFEEDBACK = 10k
15 - 75 - 50 - 25
0 25 50 75 100 125 150 TEMPERATURE (C)
1070/71 G06
1070/71 G05
Reference Voltage vs Temperature
1.250 1.248 SWITCHING FREQUENCY 42 41
SWITCHING FREQUENCY (kHz)
800 700 600 500 400 300 200 100
Feedback Bias Current vs Temperature
REFERENCE V0LTAGE
38 37 36 35
34 0 25 50 75 100 125 150 TEMPERATURE (C)
1070/71 G08
0 - 75 - 50 - 25
0 25 50 75 100 125 150 TEMPERATURE (C)
1070/71 G09
LT1070/LT1071 TYPICAL PERFORMANCE CHARACTERISTICS
Driver Current* vs Switch Current
160 140
16 15 14
DRIVER CURRENT (mA)
13 12 11 10 9 8
ISWITCH 10mA
100 80 TJ = - 55C 60 40 20 0 0 1 4 2 3 SWITCH CURRENT (A) 5
1070/71 G10
SUPPLY CURRENT (A)
INPUT CURRENT (mA)
120
TJ 25C
*AVERAGE LT1070 POWER SUPPLY CURRENT IS FOUND BY MULTIPLYING DRIVER CURRENT BY DUTY CYCLE, THEN ADDING QUIESCENT CURRENT
Normal/Flyback Mode Threshold on Feedback Pin
500 490 FEEDBACK PIN VOLTAGE (mV) 480 470 460 450 440 430 420 410 400 -50 -25 FEEDBACK PIN CURRENT (AT THRESHOLD) FEEDBACK PIN VOLTAGE (AT THRESHOLD) -24 -22 FEEDBACK PIN CURRENT (A) -20 -18 -16 -14 -12 -10 -8 -6 -4 25 50 75 100 125 150 0 TEMPERATURE (C)
1070/71 G13
TRANSCONDUCTANCE (mho)
SUPPLY CURRENT (A)
Shutdown Thresholds
400 350
VC PIN VOLTAGE (mV)
IDLE SUPPLY CURRENT (mA)
FEEDBACK VOLTAGE (mV)
CURRENT (OUT OF VC PIN)
300 250 200 VOLTAGE 150 100 50 VC VOLTAGE IS REDUCED UNTIL REGULATOR CURRENT DROPS BELOW 300A
0 - 75 - 50 - 25
0 0 25 50 75 100 125 150 TEMPERATURE (C)
1070/71 G16
UW
Supply Current vs Input Voltage*
TJ = 25C 90% DUTY CYCLE
160 140 120 100
Supply Current vs Supply Voltage (Shutdown Mode)
TJ = 25C
VC = 50mV 80 60 40 20 0 0 10 VC = 0V 20 40 30 SUPPLY VOLTAGE (V) 50 60
50% DUTY CYCLE
10% DUTY CYCLE 0% DUTY CYCLE 0 10 30 40 20 INPUT VOLTAGE (V) 50 60
7 6
1070/71 G11
1070/71 G12
*UNDER VERY LOW OUTPUT CURRENT CONDITIONS, DUTY CYCLE FOR MOST CIRCUITS WILL APPROACH 10% OR LESS
Shutdown Mode Supply Current
200 180 160 140 120 100 80 60 40 20 0 0 10 20 30 40 50 60 70 80 90 100 VC PIN VOLTAGE (mV)
1070/71 G14
Error Amplifier Transconductance
5000 4500 4000 3500 3000 2500 2000 1500 1000 500 0 -75 - 50 -25 0 25 50 75 100 125 150 TEMPERATURE (C)
1070/71 G14
gm = I (VC PIN) V (FB PIN)
TJ = 150C
- 55C TJ 125C
Idle Supply Current vs Temperature
- 400 -350 -300 -250 -200 -150 -100 - 50
VC PIN CURRENT (A)
11 10 9 8 7 6 5 4 3 2 1 -75 - 50 -25 0 25 50 75 100 125 150 TEMPERATURE (C)
1070/71 G14
Feedback Pin Clamp Voltage
500 450 400 350 300 250 200 150 100 50 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 FEEDBACK CURRENT (mA)
1070/71 G18
VC = 0.6V
- 55C 25C 150C
VSUPPLY = 60V VSUPPLY = 3V
5
LT1070/LT1071 TYPICAL PERFORMANCE CHARACTERISTICS
Switch "Off" Characteristics
1000 900 800
TRANSCONDUCTANCE (mho)
SWITCH CURRENT (A)
VC PIN CURRENT (A)
700 600 500 400 300 200 100 0 0 10 20 30 40 50 60 70 80 90 100 SWITCH VOLTAGE (V)
1070/71 G19
VSUPPLY = 3V 15V 40V 55V
BLOCK DIAGRAM
VIN 2.3V REG
40kHz OSC
MODE SELECT COMP FB
1.24V REF
OPERATION
The LT1070/LT1071 is a current mode switcher. This means that switch duty cycle is directly controlled by switch current rather than by output voltage. Referring to the Block Diagram, the switch is turned "on" at the start of each oscillator cycle. It is turned "off" when switch current reaches a predetermined level. Control of output voltage is obtained by using the output of a voltage sensing error amplifier to set current trip level. This technique has several advantages. First, it has immediate response to input voltage variations, unlike ordinary switchers which have notoriously poor line transient response. Second, it reduces the 90 phase shift at
6
UW
+ -
VC Pin Characteristics
300 200 100 0 -100 - 200 - 300 - 400 0 0.5 2.0 1.5 1.0 VC PIN VOLTAGE (V) 2.5 VFB = 1.5V (CURRENT INTO VC PIN) TJ = 25C
7000 6000 5000 4000 3000 2000 1000 0 -1000
Transconductance of Error Amplifier
- 30 0 30 gm 60 90 120 150 180 1k 10k 100k 1M FREQUENCY (Hz) 210 10M
1070/71 G21
PHASE ()
VFB = 0.8V (CURRENT OUT OF VC PIN)
1070/71 G20
W
16V SWITCH OUT FLYBACK ERROR AMP LOGIC DRIVER 5A, 75V SWITCH ANTISAT ERROR AMP VC
+
SHUTDOWN CIRCUIT 0.15V CURRENT AMP GAIN 6 0.02 (0.04 LT1071)
-
1070/71 BD
U
LT1070/LT1071
OPERATION
midfrequencies in the energy storage inductor. This greatly simplifies closed-loop frequency compensation under widely varying input voltage or output load conditions. Finally, it allows simple pulse-by-pulse current limiting to provide maximum switch protection under output overload or short-circuit conditions. A low dropout internal regulator provides a 2.3V supply for all internal circuitry of the LT1070/LT1071. This low dropout design allows input voltage to vary from 3V to 60V with virtually no change in device performance. A 40kHz oscillator is the basic clock for all internal timing. It turns "on" the output switch via the logic and driver circuitry. Special adaptive antisat circuitry detects onset of saturation in the power switch and adjusts driver current instantaneously to limit switch saturation. This minimizes driver dissipation and provides very rapid turn-off of the switch. A 1.2V bandgap reference biases the positive input of the error amplifier. The negative input is brought out for output voltage sensing. This feedback pin has a second function; when pulled low with an external resistor, it programs the LT1070/LT1071 to disconnect the main error amplifier output and connects the output of the flyback amplifier to the comparator input. The LT1070/ LT1071 will then regulate the value of the flyback pulse with respect to the supply voltage. This flyback pulse is directly proportional to output voltage in the traditional transformer coupled flyback topology regulator. By regulating the amplitude of the flyback pulse, the output voltage can be regulated with no direct connection between input and output. The output is fully floating up to the breakdown voltage of the transformer windings. Multiple floating outputs are easily obtained with additional windings. A special delay network inside the LT1070/ LT1071 ignores the leakage inductance spike at the leading edge of the flyback pulse to improve output regulation. The error signal developed at the comparator input is brought out externally. This pin (VC) has four different functions. It is used for frequency compensation, current limit adjustment, soft starting and total regulator shutdown. During normal regulator operation this pin sits at a voltage between 0.9V (low output current) and 2.0V (high output current). The error amplifiers are current output (gm) types, so this voltage can be externally clamped for adjusting current limit. Likewise, a capacitor coupled external clamp will provide soft start. Switch duty cycle goes to zero if the VC pin is pulled to ground through a diode, placing the LT1070/LT1071 in an idle mode. Pulling the VC pin below 0.15V causes total regulator shutdown, with only 50A supply current for shutdown circuitry biasing. See AN19 for full application details.
TYPICAL APPLICATIONS
Driving High Voltage FET (for Off-Line Applications, See AN25)
G D1 VIN VSW D S
D1 VIN VSW R2**
10V TO 20V
+
LT1070/LT1071
GND
1070/71 TA03
U
U
(Note that maximum output currents are divided by 2 for the LT1071) Driving High Voltage NPN
C1
D2
Q1
R1* Q1
LT1070/LT1071
*SETS IB(ON) **SETS IB(OFF)
GND
1070/71 TA16
7
LT1070/LT1071
TYPICAL APPLICATIONS
OPTIONAL INPUT FILTER L3
VIN D3 VIN C3 2.2F L2 4H VSW OPTIONAL OUTPUT FILTER R1 3.74k GND VC FB R3 470 C1 1F D1 *REQUIRED IF INPUT LEADS 2" **PULSE ENGINEERING 92112 R2 1.24k D2 1N914 C5 200F
+
LT1070
+ C5*
100F
+
- VIN
8
U
(Note that maximum output currents are divided by 2 for the LT1071) Negative Buck Converter
+
L1** 200H
D1 VIN C3 100F VSW
C2 1000F
R1 4.64k
LOAD - 5.2V 4.5A
+
LT1070
Q1 2N3906 FB C1 R3 R2 1.24k OPTIONAL OUTPUT FILTER L2 4H
1070/71 TA12
GND
VC
+
C4 200F
VIN - 20V
*REQUIRED IF INPUT LEADS 2" **PULSE ENGINEERING 92113
Positive Buck Converter
+
C2 1F L1** 100H
R4 10 5V 4.5A 100mA MINIMUM
1070/71 TA14
r
+
C4 1000F
Negative Current Boosted Buck Converter
+
R1 R5 C3 T1 1:N D1 Q1 2N3906 R4 12k R1 = VOUT - 0.6V 1mA C1 MINIMUM LOAD = 10mA
- VOUT 5V 10A
*
VIN VSW
*
LT1070
GND
VC
FB R3 C2
1070/71 TA13
R2 1.24k
LT1070/LT1071
TYPICAL APPLICATIONS
VIN 28V
+
R3 680 C5* 100F C1 0.33F
6
V V - LM308 COMP 3 4 8 200pF
+
*REQUIRED IF INPUT LEADS 2"
Negative to Positive Buck/Boost Converter
L2 L1** 150H OPTIONAL OUTPUT FILTER D1 VIN C4* 100F L3 GND OPTIONAL INPUT FILTER VIN - 12V *REQUIRED IF INPUT LEADS 2" **PULSE ENGINEERING 92113 VC VSW C2 1000F C3 D3 1N4001
+
LT1070
+
Q1
R1 11.3k
VOUT 12V 2A
C4 5F
+
LT1070
FB R3 2.2k C1 0.22F R2 1.24k
1070/71 TA05
-
+
U
(Note that maximum output currents are divided by 2 for the LT1071) Positive Current Boosted Buck Converter
470 2W D2 VSW C3 0.47F R6 470 C6 0.002F
* *
VIN
1:N
LT1070 R2 1k GND VC FB VIN 7 2 R7 1.24k
N 0.25 D1
R5 5k R4 1.24k VOUT 5V 10A C2 5000F
1070/71 TA19
R1 5k
+
Positive to Negative Buck/Boost Converter
R5 470 1W TO AVOID START-UP PROBLEMS FOR INPUT VOLTAGES BELOW 10V, VIN 10V TO 30V CONNECT ANODE OF D3 TO VIN AND REMOVE R5. C5* C1 MAY BE REDUCED FOR 100F LOWER OUTPUT CURRENTS. C1 (500F)(IOUT) FOR 5V OUTPUTS, REDUCE R3 TO 1.5k, INCREASE C2 TO 0.3F D2 R1 R4 1N914 47 AND REDUCE R6 TO 100. 10.7k
VIN
VSW
GND
VC
FB R3 5k C1 0.1F R2 1.24k
+
C3 C1 2F 1000F D1
+
R6 470 VOUT - 12V 2A
1070/71 TA09
L1** 200H
*REQUIRED IF INPUT LEADS 2" **PULSE ENGINEERING 92113
9
LT1070/LT1071
TYPICAL APPLICATIONS
R4 680 1W D2 VIN VIN 15V
Voltage Boosted Boost Converter
C3 0.68F TOTAL INDUCTANCE = 4mH INTERLEAVE PRIMARY AND SECONDARY FOR LOW LEAKAGE INDUCTANCE VOUT 100V 300mA
+
LT1070
VSW
1 L1 N=5 D1
R1 98k GND VC FB R3 10k C2 0.047F R2 1.24k
+
1070/71 TA10
Negative Boost Regulator
D2 VIN
VSW
C4* 470F
+
LT1070
R1 27k
+
GND VC FB R3 3.3k C2 0.22F R2 1.24k
VIN -15V
L1 200H
*REQUIRED IF INPUT LEADS 2"
External Current Limit
VIN
VSW
LT1070/LT1071
+
VIN GND R1 1k Q1 C1 1000pF RS VC FB
R2
1070/71 TA04
C2
10
U
(Note that maximum output currents are divided by 2 for the LT1071) Current Boosted Boost Converter
R4
C3
I N
D1
D2 VIN VIN 16V TO 24V
VOUT 28V 4A
+
LT1070
VSW R1 27k
+
C1 FB R3 C2 R2 1.24k
GND
VC
C1 200F
1070/71 TA11
Negative Input/Negative Output Flyback Converter
* *
Q1 2N3906 R1* LT1070/LT1071 - VOUT GND VC FB R5 *R1 = R4 1.24k
1070/71 TA17
C3
R6
R3 1k
R2 5k
VIN
+
C3 10F
VSW
C1 1000F
RO (MINIMUM LOAD)
T1 1:N
+
C1
+
VOUT - 1.6V 200A
D1
VOUT -28V 1A
C2 - VIN
1070/71 TA15
External Current Limit
VX LT1070/LT1071 R2 = 2V D1 R1 500 GND VC
NOTE THAT THE LT1070/LT1071 GND PIN IS NO LONGER COMMON TO VIN- 1070/71 TA06
LT1070/LT1071
TYPICAL APPLICATIONS
VIN 20V TO 30V R4
C3 0.47F D2
VIN
VSW N = 1/3 R1 3.74k 0 IPRI N 0 IPRI R2 1.24k 0 IPRI
+
C4* 100F
LT1070 FB GND VC R3 1.5k C2 0.15F
*REQUIRED IF INPUT LEADS 2"
PACKAGE DESCRIPTION
K Package 4-Lead TO-3 Metal Can
(LTC DWG # 05-08-1311)
0.320 - 0.350 (8.13 - 8.89) 0.760 - 0.775 (19.30 - 19.69) 0.060 - 0.135 (1.524 - 3.429)
0.420 - 0.480 (10.67 - 12.19)
0.038 - 0.043 (0.965 - 1.09) 1.177 - 1.197 (29.90 - 30.40) 0.655 - 0.675 (16.64 - 19.05) 0.151 - 0.161 (3.84 - 4.09) DIA 2 PLC 0.167 - 0.177 (4.24 - 4.49) R 72 18 0.495 - 0.525 (12.57 - 13.34) R
0.470 TP P.C.D.
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
U
U
(Note that maximum output currents are divided by 2 for the LT1071) Flyback Converter
VSNUB L2 10H OPTIONAL FILTER D1 C4 200F VOUT 5V 6A C1 2000F VIN 0V VOUT + VF c 0V d I IPRI PRIMARY CURRENT (N)(VIN) SECONDARY VOLTAGE AREA "c" = AREA "d" TO MAINTAIN ZERO DC VOLTS ACROSS SECONDARY CLAMP TURN-ON SPIKE
a b
+ VF V PRIMARY FLYBACK VOLTAGE = OUT N LT1070/LT1071 SWITCH VOLTAGE AREA "a" = AREA "b" TO MAINTAIN ZERO DC VOLTS ACROSS PRIMARY
*
1N
+
*
SECONDARY CURRENT
LT1070 SWITCH CURRENT
SNUBBER DIODE CURRENT (I )(L ) t = PRI L VSNUB
1070/71 TA08
Dimensions in inches (millimeters) unless otherwise noted. T Package 5-Lead Plastic TO-220 (Standard)
(LTC DWG # 05-08-1421)
0.147 - 0.155 (3.734 - 3.937) DIA 0.230 - 0.270 (5.842 - 6.858) 0.460 - 0.500 (11.684 - 12.700) 0.570 - 0.620 (14.478 - 15.748) 0.330 - 0.370 (8.382 - 9.398) 0.700 - 0.728 (17.78 - 18.491) 0.620 (15.75) TYP 0.165 - 0.180 (4.191 - 4.572)
0.390 - 0.415 (9.906 - 10.541)
0.045 - 0.055 (1.143 - 1.397)
0.152 - 0.202 0.260 - 0.320 (3.861 - 5.131) (6.60 - 8.13)
0.095 - 0.115 (2.413 - 2.921)
0.013 - 0.023 (0.330 - 0.584) 0.057 - 0.077 (1.448 - 1.956) 0.028 - 0.038 (0.711 - 0.965) 0.135 - 0.165 (3.429 - 4.191) 0.155 - 0.195 (3.937 - 4.953)
T5 (TO-220) 0398
K4(TO-3) 0695
11
LT1070/LT1071
TYPICAL APPLICATIONS
+V
+
IN
5V
C5* 100F
LT1070/LT1071 FB GND VC
*REQUIRED IF INPUT LEADS 2"
VIN 20V TO 30V
GND
RELATED PARTS
PART NUMBER
LT1074/LT1076 LT1170/LT1171/ LT1172 LT1370/LT1371 LT1374/LT1376
DESCRIPTION
High Voltage Switching Regulators 100kHz High Efficiency Switching Regulators 500kHz High Efficiency Switching Regulators 100kHz High Efficiency Switching Regulators
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
U
(Note that maximum output currents are divided by 2 for the LT1071) Totally Isolated Converter
OPTIONAL OUTPUT FILTER D1 1:N R4 1.5k C3 0.47F L1 10F
15V
*
+
N
C1 500F C4 500F
+
COM L2 10F
C5 200F C6 200F
N VIN VSW N = 0.875 = 7:8 FOR VOUT = 15V
+
+
*
-15V
16V SWITCH VOLTAGE 500 VIN 0V R2 tOFF tON VOUT 0V VF (DIODE FORWARD VOLTAGE) SECONDARY VOLTAGE
1070/71 TA07
C2 5k 0.01F
(N)(VIN)
Forward Converter
T1 R4 C2 D3 VSW D4 R1 3.74k D1 N L1 70H VOUT 5V 6A C1 2000F
*
I
M
*
+
D2
VIN
*
LT1070
VC
FB Q1 R3 C3 R6 C4 330 R5 1 R2 1.24k
1070/71 TA18
COMMENTS
40V Input (60V for HV Versions), 100kHz, 5A and 2A 40V Input (65V for HV Versions), 5A/2.5A/1.25A Internal Switch 35V, 6A/3A Internal Switch 25V Input, 4.5A/1.5A Internal Switch
10701fd LT/TP 1098 2K REV D * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1989

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