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Part: LT1269CQ
Category:
Power Management
-> Regulators
-> Switching Regulators
Description: 4a High Efficiency Switching Regulators
Company: Linear Technology Corporation
Datasheet: Download LT1269CQ datasheet File size : 467 kB
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Datasheet text preview:
LT1271/LT1269 4A High Efficiency Switching Regulators FEATURES
s s s s s s s s s
DESCRIPTIO
Wide Input Voltage Range 3.5V to 30V Low Quiescent Current: 7mA Internal 4A Switch Very Few External Parts Required Self Protected Against Overloads Shutdown Mode Draws Only 100µA Supply Current Flyback Regulated Mode Has Fully Floating Outputs Comes in Standard 5-Pin Package Can Be Externally Synchronized (See LT1072 Data Sheet)
APPLICATI
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S
Boost Converter High Efficiency Buck Converter PC Power Supply with Multiple Outputs Battery Up-Converter Negative-to-Positive Converter
The LT®1271 and LT1269 are monolithic high power switching regulators. Identical to the popular LT1070, except for switching frequency (LT1271 = 60kHz, LT1269 = 100kHz) and slightly lower switch current, they can be operated in all standard switching configurations including buck, boost, flyback and inverting. 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 LT1271/LT1269 to be built in a standard TO-220 power package. This makes them extremely easy to use and provides "bust proof" operation similar to that obtained with 3-pin linear regulators. The LT1271/LT1269 operate with supply voltages from 3.5V to 30V, and draw only 7mA quiescent current. By utilizing current mode switching techniques, they provides excellent AC and DC load and line regulation. A patented adaptive antisat switch drive allows very wide ranging load currents with no loss in efficiency. An externally activated shutdown mode reduces total supply current to 100µA typical for standby operation.
, LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation.
USER NOTE: This data sheet is only intended to provide specifications, graphs, and a general functional description of the LT1271/LT1269. Application circuits are included to show the capability of the LT1271/LT1269. A complete design manual (AN-19) 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 LT1271/LT1269 by factoring in the higher switch current rating and higher operating frequency.
TYPICAL APPLICATION
High Efficiency 5V Regulator with Burst ModeTM Operation
50
6
VIN .5V TO 25V
VSW LT1271 FB VC 0.0 2µF 80 .1µF 6
VIN
OUTPUT POWER (W)
EFFICIENCY 90% AT IOUT = 0.4A TO 1.5A GND N4148
0.03µF 4.7µF TANT
+
2 L1 T 5µH 1 O 50µH
0.015
3MBR 30pF V+ VLIM LT1432 VOUT MODE GND
+
V 5 OUT V, 3A 1 390µF 6V
VC 2 C1 03 µF 0 5V
DIODE
+
VIN
2.5V = SHUTDOWN OPEN = BURST MODE OPERATION
127/691 TA01
U
Maximum Output Power
40 BOOST BUCK-BOOST V O = 12V (INVERTING) 30 FLYBACK 20 BUVK-BOOST C O = 5V (INVERTING) 0 5 15 20 10 INPUT VOLTAGE (V) 25 30 10 0
1271/69 TA02
U
UO
T BUCK MODE OUTPUT POWER (3.5A)(VOUT) RANSFORMER TURNS RATIO MUST BE OPTIMUM TO ACHIEVE FULL POWER.
1
LT1271/LT1269 ABSOLUTE AXI U RATI GS
Operating Junction Temperature Range Operating .... 0°C to 100°C Short Circuit ........ 0°C to 125°C Lead Temperature (Soldering, 10 sec.)....... 300°C
Supply Voltage ....... 30V Switch Output Voltage ........... 60V Feedback Pin Voltage (Transient, 1ms) ....... ±15V Storage Temperature Range ....... 65°C to 150°C
PACKAGE/ORDER I FOR ATIO
FRONT VIEW 4 5 3 2 1 VIN GSW F ND VB
C
ORDER PART NUMBER
2 VSW 1
LT1271CQ LT1269CQ
S OWER P WITCH
Q PACKAGE 5-LEAD PLASTIC DD TJ MAX = 100°C, JC = 4°C/W, JA = 30°C/W* FRONT VIEW 4 5 3 2 1 VIN GSW F ND VB
C
ORDER PART NUMBER LT1271CT LT1269CT
T PACKAGE 5-LEAD PLASTIC TO-220 TJ MAX = 100°C, JC = 4°C/W, JA = 50°C/W
* With device soldered to 1/2 square inch of 1oz copper over backside or internal layer ground plane. Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL V REF 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 (Note 3) Supply Current
VIN = 15V, VC = 0.5V, VFB = VREF, switch pin open, unless otherwise noted.
MIN
q q
CONDITIONS Measured at Feedback Pin VC = 0.8V VFB = VREF IC = ±25µA
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
2
U
U
W
WW
U
W
TOP VIEW 1V 20 VSW 19 NSW 18 GC 17 GND 16 GND 15 GND 14 V ND 13 NIN 12 NC 0 1 C S POWER WITCH
ORDER PART NUMBER LT1269CS
N SW 3 GC 4 GND 5 GND 6 GND 7 A ND 8 GND 9 V FC 1 VB
SW PACKAGE 20-LEAD PLASTIC WIDE SO
WILL VARY FROM APPROXIMATELY 40°C/W WITH 0.75 SQ. IN. OF 1 OZ. COPPER TO 46°C/W WITH 0.33 SQ. IN. OF 1 OZ. COPPER
TYP 1.244 1.244 350
MAX 1.264 1.274 750 1100 6000 7000 350 400 2.3 0.52 0.03
UNITS V V nA nA µmho µmho µA µA V V %/V V/V
1.224 1.214
3000 2400 150 120 1.8 0.25
4400 200
0.38
500
800 2.8 7 3.0 10
V mA
LT1271/LT1269
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER Control Pin Threshold Normal/Flyback Threshold on Feedback Pin V FB V FB Flyback Reference Voltage Change in Flyback Reference Voltage Flyback Reference Voltage Line Regulation Flyback Amplifier Transconductance (gm) Flyback Amplifier Source and Sink Current BV VSAT Output Switch Breakdown Voltage Output Switch (Note 1) "On" Resistance Control Voltage to Switch Current Transconductance I LIM IIN ISW f DC (max) Switch Current Limit (Note 2) Supply Current Increase During Switch On-Time Switching Frequency 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
VIN = 15V, VC = 0.5V, VFB = VREF, switch pin open, unless otherwise noted.
MIN
q
CONDITIONS Duty Cycle = 0
TYP 0.9 0.45 16.3 6.8 0.01
MAX 1.08 1.25 0.54 17.6 18 8.5 0.03 650 70 70
UNITS V V V V V V %/V µmho µA µA V
0.7 0.5 0.4
IFB = 50µA
q
15 14 4.5
0.05 IFB 1mA IFB = 50µA 3V VIN VMAX IC = ±10µA VC = 0.6V IFB = 50µA 3V VIN VMAX ISW = 1.5mA Source Sink
q q q q
150 15 25 60
300 32 40 75 0.2 6.4
0.33
A/V
Duty Cycle = 50% Duty Cycle = 80%
q q
4 3.2 25
8 8 40 70 115 95 95 400 250 300
A A mA/A kHz kHz % % µs µA mV mV
LT1271 LT1269 LT1271 LT1269
q q
50 85 85 80
60 100 92 90 1.5 100
100 50
150
The q denotes the specifications which apply over the full operating temperature range. Note 1: Measured with VC in hi clamp, VFB = 0.8V.
Note 2: For duty cycles (DC) between 50% and 85%, minimum guaranteed switch current is given by ILIM = 2.67 (2 DC). Note 3: Minimum input voltage.
3
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