LTC1430A Linear Technology, LTC1430A Datasheet
LTC1430A
Available stocks
Related parts for LTC1430A
LTC1430A Summary of contents
Page 1
... The LTC1430A’s maximum duty cycle is typically 93.5% com- pared to 88% for the LTC1430. This permits 3.3V to 2.xV conversion using a low power 5V supply. The LTC1430A features low 350 A quiescent current, allowing greater ® than 90% efficiency operation in converter designs from 1A to greater than 50A output current ...
Page 2
... Internal Oscillator Frequency OSC (Note 1) Junction Temperature ........................................... 150 C Operating Temperature Range LTC1430AC ............................................. LTC1430AI ........................................ – Storage Temperature Range ................ – 150 C Lead Temperature (Soldering, 10 sec)................. 300 C + 0.3V ORDER PART NUMBER 1 G1 LTC1430ACS8 2 PV CC1 ...
Page 3
... V , COMP 1.265V FB the LTC1430A operating frequency, operating voltage and the external FETs used. Note 4: The I amplifier can sink but cannot source current. Under LIM normal (not current limited) operation, the I Note 5: The open-loop DC gain and transconductance from the FB pin ...
Page 4
... LTC1430A W U TYPICAL PERFOR A CE CHARACTERISTICS I Pin Sink Current MAX vs Temperature 14 13.5 13.0 12.5 12.0 11.5 11.0 10.5 – 40 – 100 TEMPERATURE ( C) 1430 G01 Error Amplifier Transconductance vs Temperature 850 I COMP g = 800 750 700 650 600 550 500 450 400 350 – 40 – ...
Page 5
... SENSE nal resistor divider to FB. SHDN (Pin 8/Pin 5): Shutdown. A TTL compatible low level at SHDN for longer than 50 s puts the LTC1430A into shutdown mode. In shutdown, G1 and G2 go low, all internal circuits are disabled and the quiescent current drops max. A TTL compatible high level at SHDN allows the part to operate normally ...
Page 6
... F 6 PGND GND + SENSE FB NC – SENSE Q1A, Q1B, Q2: MOTOROLA MTD20N03HL C : AVX-TPSE227M010R0100 AVX-TPSE337M006R0100 OUT Figure PGND MAX 20k SENSE 40mV 12.4k SENSE 1430 BD FB MEASUREMENT V OUT LTC1430A + 1.61k SENSE NC FB 3.3V – SENSE 1k NC 1430 F01 CC1 CC2 FB + – ...
Page 7
... SENSE C Q1A, Q1B, Q2: MOTOROLA MTD20N03HL 4700pF C : AVX-TPSE227M010R0100 AVX-TPSE337M006R0100 OUT Figure 4 LTC1430A CC1 CC2 CC COMP G1 G1 RISE/FALL 10,000pF LTC1430A RISE/FALL GND PGND 10,000pF Figure 220 F 4 Q1A, Q1B 2 IN PARALLEL 2.7 H/15A 0 OUT Q2 330 F ...
Page 8
... The 8-lead version does not include current limit, internal soft start or frequency adjustability. THEORY OF OPERATION Primary Feedback Loop The LTC1430A senses the output voltage of the circuit at the output capacitor with the SENSE and feeds this voltage back to the internal transconduc- tance amplifier FB. FB compares the resistor-divided out- put voltage to the internal 1 ...
Page 9
... Another feature of the synchronous architecture is that PV CC unlike a diode, Q2 can conduct current in either direction. This allows the output of a typical LTC1430A circuit to sink current as well as sourcing it while remaining in regula- tion. The ability to sink current at the output allows the Q1 LTC1430A to be used with reactive or other nonconventional ...
Page 10
... Once the threshold voltage has been selected chosen based on input and output voltage, allowable power dissipation and maximum required output current typical LTC1430A buck converter circuit operating in continuous mode, the average inductor current is equal to D 1N5817 ...
Page 11
... Motorola MTD20N03HL (in DPAK) are two small, surface mount devices with R values of 0.03 or below with gate drive; both work well in LTC1430A circuits with up to 10A output current. A higher P MAX decrease MOSFET cost and circuit efficiency and increase MOSFET heat sink requirements. ...
Page 12
... AVX TPS series surface mount devices are popular tantalum capaci- tors that work well in LTC1430A applications. A common way to lower ESR and raise ripple current capability is to parallel several capacitors. A typical LTC1430A applica- ...
Page 13
... The LTC1430A can be used with input supply voltages lower than 5V as long as a low power 5V supply is available to PV while CC1 to power the LTC1430A itself and to provide gate drive to is the ON F the external MOSFETs. A typical 3.3V to 2.5V application is shown in Figure 10. The circuit can supply up to 10A ...
Page 14
... Soft start functions by clamping the maximum 820pF 33 voltage that the COMP pin can swing to, thereby control- 470pF 15 ling the duty cycle (Figure 12). The LTC1430A will begin to 0.0022 82 operate at low duty cycle as the SS pin rises to about 2V 0.001 39 below V CC 470pF ...
Page 15
... At this point all switching stops, the output current decays through Q2 and the LTC1430A runs a partial soft start FB cycle and restarts. If the short is still present the cycle will Q2 repeat. Peak currents can be quite high in this condition, ...
Page 16
... A clock signal applied directly to the SHDN pin will force the LTC1430A internal oscillator to lock to its frequency as long as the external clock runs faster than the internal oscillator frequency ...
Page 17
... Power Component Hook-Up/Heat Sinking As current levels rise much above 1A, the power compo- nents supporting the LTC1430A start to become physi- cally large (relative to the LTC1430A, at least) and can require special mounting considerations. Input and output capacitors need to carry high peak currents and must have low ESR ...
Page 18
... CD4047, a low cost, CMOS mulitvibrator with a built-in divide-by-two flip flop. The CD4047 oscillator is set to run at 600kHz and the Q and Q outputs drive the LTC1430A shutdown pins. Since the sync signals are derived from the clock’s divide-by-two outputs, they are inherently 180 out of phase and at the desired 300kHz clock fre- quency. Q1, D1 and the two resistors connected to Q1’ ...
Page 19
... PPLICATI FOR ATIO W U LTC1430A 19 ...
Page 20
... LTC1430A PPLICATI S I FOR ATIO the sense resistors should be well matched. This is accomplished by using trace resistors that are laid out symmetrically. Since they are formed of the same material and processed identically, they will inherently match very well. Note that the absolute value of these resistors is not important ...
Page 21
... TYP 0.008 – 0.012 (0.203 – 0.305) LTC1430A 0.189 – 0.196* (4.801 – 4.978) 0.009 (0.229 REF 0.150 – 0.157** (3.810 – 3.988) ...
Page 22
... LTC1430A PACKAGE DESCRIPTIO 0.010 – 0.020 (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 0.016 – 0.050 0.406 – 1.270 * DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" ...
Page 23
... DWG # 05-08-1610 0.228 – 0.244 (5.791 – 6.197 0.053 – 0.069 (1.346 – 1.752) 0 – 8 TYP 0.014 – 0.019 (0.355 – 0.483) LTC1430A 0.386 – 0.394* (9.804 – 10.008 0.150 – 0.157** (3.810 – 3.988) 3 ...
Page 24
... FAX: (408) 434-0507 www.linear-tech.com GTL Terminator D1 MBR0530T1 C10 C16 CC2 CC1 Si4410 11 13 FSET I FB LTC1430A MAX SHDN PGND COMP – SENSE +SENSE 4 6 SGND FB Q2 Si4410 ...