LTC1430 LINER [Linear Technology], LTC1430 Datasheet
LTC1430
Available stocks
Related parts for LTC1430
LTC1430 Summary of contents
Page 1
... N-channel FET, providing an adjustable current limit without an external low value sense resistor. The LTC1430 includes a fixed frequency PWM oscillator for low output ripple under virtually all operating conditions. The 200kHz free-running clock frequency can be externally adjusted from 100kHz to above 500kHz ...
Page 2
... CC IPV Supply Current ( Internal Oscillator Frequency OSC 2 U (Note 1) Operating Temperature Range LTC1430C .............................................. LTC1430I ........................................... – Storage Temperature Range ................ – 150 C Lead Temperature (Soldering, 10 sec)................. 300 C + 0.3V ORDER PART NUMBER CC1 LTC1430CN8 ...
Page 3
... FB Note 4: Supply current in normal operation is dominated by the current needed to charge and discharge the external FET gates. This will vary with the LTC1430 operating frequency, operating voltage and the external FETs used. Note 5: The I amplifier can sink but cannot source current. Under ...
Page 4
... SENSE connect the external resistor divider to FB. SHDN (Pin 8/Pin 5): Shutdown. A TTL compatible low level at SHDN for longer than 50 s puts the LTC1430 into shutdown mode. In shutdown, G1 and G2 go low, all internal circuits are disabled and the quiescent current drops max ...
Page 5
... 20.1k + SENSE 40mV 12.4k – SENSE LTC1430 • MEASUREMENT V OUT LTC1430 + 1.61k SENSE NC FB 3.3V – SENSE C 1k OUT 330 LTC1430 • F01 0 CC1 CC2 RISE/FALL 10,000pF LTC1430 G2 G2 RISE/FALL PGND GND 10,000pF LTC1430 • TC03 Figure 3 5 ...
Page 6
... The 8-lead versions do not include current limit, internal soft-start or frequency adjustability. THEORY OF OPERATION Primary Feedback Loop The LTC1430 senses the output voltage of the circuit at the + output capacitor with the SENSE feeds this voltage back to the internal transconductance amplifier FB. FB compares the resistor-divided output voltage to the internal 1 ...
Page 7
... The current drawn from this supply varies with the MOSFETs used and the LTC1430’s operating frequency, but is generally less than 50mA. LTC1430 designs that use a doubler charge pump to generate gate drive for M1 and run from PV below 7V cannot provide enough gate drive voltage to fully enhance standard power MOSFETs ...
Page 8
... To minimize this effect, the inductor value should usually be in the range for most typical 5V to 3.xV LTC1430 circuits. Different combinations of input and output voltages and expected loads may require different values. ...
Page 9
... ESR. During an output load transient, the output capacitor must supply all of the additional load current demanded by the load until the LTC1430 can adjust the inductor current to the new value. ESR in the output capacitor results in a step in the output voltage equal to the ESR value multiplied by the change in load current ...
Page 10
... CC CC2 CC1 G1 INTERNAL CIRCUITRY G2 LTC1430 (16-LEAD) Figure 6. 16-Lead Power Supplies The 8-lead versions of the LTC1430 have the PV V pins tied together inside the package (Figure 7). This CC pin, brought out as V /PV , has the same low ripple CC CC2 requirements as the 16-lead part, but must also be able to supply the gate drive current to M2 ...
Page 11
... Soft-start functions by clamping the maximum 0.001 39 voltage that the COMP pin can swing to, thereby control- 0.0047 150 ling the duty cycle (Figure 9). The LTC1430 will begin to 0.0022 82 operate at low duty cycle as the SS pin rises to about 2V 820pF 33 below V CC 470pF ...
Page 12
... I the I LIM LTC1430 goes deeper into current limit, it will reach a point where the M1 on-time needs to be cut to below 170ns to control the output current. This conflicts with the mini- mum settling time needed for proper operation of the I amplifier ...
Page 13
... CC Output Voltage Sensing The LTC1430 provides three pins for sensing the output voltage: SENSE connect to an internal resistor divider which is connected to FB. To set the output of the LTC1430 to 3.3V, connect + SENSE to the output as near to the load as practical and connect SENSE that SENSE is just the bottom of the internal divider string. Connecting – ...
Page 14
... LTC1430 • F12 100 1 F 1N4148 CC2 PGND PV CC1 G1 LTC1430 0 MAX I FREQSET FB + SENSE SHDN G2 COMP FB NC – SS SENSE GND PGND suitable TOTAL 880 F (220 F 10V 4) M1A* M1B* 2.7 H/15A 3.3V + TOTAL M2* 1980 F (330 F 6.3V 6) PGND * MOTOROLA MTD20N03HL LTC1430 • F11 ...
Page 15
... BSC N Package 14-Lead PDIP (Narrow 0.300) (LTC DWG # 05-08-1510) 0.045 – 0.065 (1.143 – 1.651) 0.065 (1.651) TYP 0.018 0.003 0.100 (2.54) (0.457 0.076) BSC LTC1430 0.400* (10.160) MAX 0.255 0.015* (6.477 0.381 1098 0.770* (19 ...
Page 16
... LTC1430 PACKAGE DESCRIPTIO 0.010 – 0.020 45 (0.254 – 0.508) 0.008 – 0.010 0 – 8 TYP (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" ...