LTC3828 LINER [Linear Technology], LTC3828 Datasheet
LTC3828
Available stocks
Related parts for LTC3828
LTC3828 Summary of contents
Page 1
... The TRCKSS pin provides both soft-start and tracking functions. Multiple LTC3828s can be daisy-chained in applications requiring more than two voltages to be tracked. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values ...
Page 2
... Peak Output Current <10µs (TG1, TG2, BG1, BG2 INTV Peak Output Current ................................ 50mA CC Operating Temperature Range (Note 7) LTC3828E .......................................... – 40°C to 85°C Junction Temperature (Note 2) ............................ 125°C Storage Temperature Range ................ – 65°C to 125°C to – 0.3V CC Reflow Peak Body Temperature (UH Package) .... 260°C Lead Temperature (Soldering, 10 sec) to – ...
Page 3
... PLLFLTR ≥ 2.4V V PLLFLTR f < f PLLIN OSC f > f PLLIN OSC I = 2mA PGOOD PGOOD V with Respect to Set Output Voltage OSENSE V Ramping Negative OSENSE V Ramping Positive OSENSE LTC3828 MIN TYP MAX UNITS 3 MHz µA 20 100 ● 0.76 0.800 0.84 V µA – 0.50 – 0.18 – 0.1 4.3 4.8 V ● 3.5 ...
Page 4
... A Note 6: The minimum on-time condition is specified for an inductor peak-to-peak ripple current ≥ 40 considerations in the Applications Information section). Note 7: The LTC3828E is guaranteed to meet performance specifications to a ITH1, 2 over the –40°C to 85°C operating temperature range as assured by design, OSENSE1, 2. ...
Page 5
... Maximum Current Sense Threshold vs Percent of Nominal Output Voltage (Foldback 0.25 0.5 0.75 1.0 PERCENT ON NOMINAL OUTPUT VOLTAGE (%) 3828 G14 LTC3828 Current Sense Pin Input Current vs Temperature –50 – 100 125 TEMPERATURE (°C) 3828 G09 Load Regulation ...
Page 6
... LTC3828 W U TYPICAL PERFOR A CE CHARACTERISTICS Current Sense Threshold vs I Voltage –10 –20 0 0.5 1.0 1.5 2.0 V (V) ITH 3828 G16 Soft Start-Up: (Figure 14, with Coincident Tracking) V OUT1 1V/DIV V OUT2 1V/DIV 5ms/DIV V = 12V OUT1 V = 3.3V OUT2 3828 G19 Load Step: Burst Mode Operation ...
Page 7
... Input and External Synchronization Input to Phase Detec- tor. Pulling this pin below 0.8V will force continuous synchronous operation. Feeding an external clock signal will synchronize the LTC3828 to the external clock. SGND (Pin 9/Pin 6): Small Signal Ground. Common to both controllers, this pin must be routed separately from high current grounds to the common (– ...
Page 8
... LTC3828 CTIO S TG2, TG1 (Pins 17, 25/Pins 16, 25): High Current Gate Drives for Top N-Channel MOSFETs. These are the outputs of floating drivers with a voltage swing equal to INTV 0.5V superimposed on the switch node voltage SW. SW2, SW1 (Pins 18, 24/Pins 17, 24): Switch Node Connections to Inductors. Voltage swing at these pins is ...
Page 9
... I2 3mV SENSE 30k 45k 45k 1.2µA V OSENSE 2. – TRCKSS 0.80V OV + – 0.86V I TH SHDN RUN RST SOFT 4(V ) START FB RUN Figure 1 LTC3828 V IN DRV CC INTV SGND (UH PACKAGE PAD) DRV SENSE + – ...
Page 10
... FCB/PLLIN pin acts as the input for exter- nal clock synchronization. Upon detecting the presence of an external clock signal, channel 1 will lock on to this external clock and this will be followed by channel 2 (see Frequency Synchronization section). The LTC3828 de- faults to forced continuous mode when sychronized to an external clock. pin below TH pin ...
Page 11
... If a short is present, a safe, low output current is provided due to , Burst Mode CC internal current foldback and actual power wasted is low due to the efficient nature of the current mode switching regulator. This function is disabled at start-up. LTC3828 3828f 11 ...
Page 12
... N(MEAS) (a) Figure 2. Input Waveforms Comparing Single-Phase (a) and 2-Phase (b) Operation for Dual Switching Regulators Converting 12V to 5V and 3. Each. The Reduced Input Ripple with the LTC3828 2-Phase Regulator Allows Less Expensive Input Capacitors, Reduces Shielding Requirements for EMI and Improves Efficiency 12 ...
Page 13
... Functional Diagram APPLICATIO S I FOR ATIO Output Voltage Tracking The LTC3828 allows the user to program how the channel outputs ramp up and down by means of the TRCKSS pins. Through these pins, the channel outputs can be set up to either coincidentally or ratiometrically tracking, as shown in Figure 4. ...
Page 14
... Figure system that requires more than two tracked supplies, multiple LTC3828s can be daisy-chained through the TRCKSS1 pin. TRCKSS1 clamps channel 1’s reference in the same manner TRCKSS2 clamps channel 2. To elimi- nate the possibility of multiple LTC3828s coming OUT1 R3 R1 ...
Page 15
... The operating frequency and inductor selection are inter- related in that higher operating frequencies allow the use of smaller inductor and capacitor values. So why would anyone ever choose to operate at lower frequencies with larger components? The answer is efficiency. A higher frequency generally results in lower efficiency because of LTC3828 V OUT1 V OUT3 V ...
Page 16
... This results in an abrupt increase in inductor ripple current and consequent output voltage ripple. One advantage of the LTC3828 is its current mode control that detects and limits cycle-by-cycle peak inductor current. Therefore, accurate and fast protection ...
Page 17
... As little as one 22µF or two to three 10µF ceramic capaci- tors are an ideal choice in a 20W to 35W power supply due to their extremely low ESR. Even though the capacitance at 20V is substantially below their rating at zero-bias, very low ESR loss makes ceramics an ideal candidate for LTC3828 Selection OUT is simplified by the multiphase archi- IN ...
Page 18
... Sanyo POSCAP or Panasonic SP capacitor can be used in parallel with ceramic capacitors. Other high performance electolytic capacitor manufactur- ers include AVX, KEMET and NEC. With LTC3828, a combination of ceramic and low ESR electrolytic capaci- tors can provide a low ripple, fast transient, high density and cost-effective solution ...
Page 19
... V OSENSE RUN and Soft-Start The LTC3828 RUN pins shut down their respective chan- nels independently. The LTC3828 is put in a low quiescent current state (I below 1V. TRCKSS pins are actively pulled to ground in this shutdown state. Once the RUN pin voltages are above 1.5V, the respective channel of the LTC3828 is powered LTC3828 ⎛ ...
Page 20
... The internal soft-start timer will also be in effect if the LTC3828 is trying to track an output supply that is already powered up. In any case, the force continuous mode is disabled and PGOOD signal is forced low during the first 90% of the soft-start phase ...
Page 21
... Figure 10). ) smooth out the LP is 0.01µ LTC3828 is the smallest time duration ON(MIN) V < OUT ) INTV LTC3828 3828 F10 Figure 10. Active Voltage Positioning Applied to the LTC3828 pin with a 3828f 21 ...
Page 22
... 40µF of capacitance having a maximum of 20mΩ to 50mΩ of ESR. The LTC3828 2-phase architecture typically halves this input capacitance requirement over competing solu- tions. Other losses including Schottky conduction losses during dead-time and inductor core losses generally ac- count for less than 2% total additional loss. ...
Page 23
... The network shown in Figure 11 is the most straightfor- ward approach to protect a DC/DC converter from the ravages of an automotive power line. The series diode LTC3828 and the bandwidth of the loop will increased by the same ...
Page 24
... Note that the transient suppressor should not conduct during double-battery operation, but must still clamp the input voltage below breakdown of the converter. Although the LTC3828 have a maximum input voltage of 30V, most applications will also be limited to 30V by the MOSFET BVD ...
Page 25
... All of these nodes have very large and fast moving signals and therefore should be kept on the “output side” of the LTC3828 and occupy minimum PC trace area. 7. Use a modified “star ground” technique: a low imped- ance, large copper area central grounding point on the same side of the PC board as the input and output (– ...
Page 26
... LTC3828 U U APPLICATIO S I FOR ATIO Figure 12. LTC3828 Recommended Printed Circuit Layout Diagram PULL_UP <5.5V 28 CLKOUT PGOOD TRCKSS1 27 I PGOOD TH1 LTC3828 26 + BOOST1 SENSE1 25 – TG1 SENSE1 24 V SW1 ...
Page 27
... APPLICATIO S I FOR ATIO BOLD LINES INDICATE HIGH SWITCHING CURRENT. KEEP LINES TO A MINIMUM LENGTH SW1 L1 D1 CERAMIC SW2 L2 D2 CERAMIC Figure 13. Branch Current Waveforms LTC3828 R V SENSE1 OUT1 + C R OUT1 SENSE2 OUT2 + C R OUT2 L2 3728 F11 3828f 27 ...
Page 28
... LTC3828 U U APPLICATIO S I FOR ATIO Start with one controller time helpful to use a DC-50MHz current probe to monitor the current in the inductor while testing the circuit. Monitor the output switching node (SW pin) to synchronize the oscilloscope to the internal oscillator and probe the actual output voltage as well ...
Page 29
... INTVCC 4.7µF 20 BG1 19 BG2 18 – SW2 17 + TG2 C B2 0.22µF 16 BOOST2 15 RUN2 10Ω 2nF 10Ω Figure 14. LTC3828 High Efficiency Low Noise 5V/3A, 3.3V/5A, Regulator with Ratiometric Tracking LTC3828 L1 R SENSE1 4.7µH 0.015Ω V OUT1 1µF CERAMIC R IN 10Ω C OUT1 150µF 6.3V ...
Page 30
... PGND C INTVCC 4.7µF 20 BG1 19 BG2 18 – SW2 17 + TG2 C B2 0.22µF 16 BOOST2 15 RUN2 10Ω 2nF 10Ω Figure 15. LTC3828 High Efficiency Low Noise 1.5V/7A, 3.3V/7A, 500kHz Regulator with Ratiometric Tracking L1 R SENSE1 0.68µH 6mΩ V OUT1 1. 1µF CERAMIC R IN 10Ω C OUT1 330µF 2. VIN 22µ ...
Page 31
... M0-220 VARIATION WHHD-(X) (TO BE APPROVED) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED LTC3828 9.90 – 10.50* (.390 – .413 7.40 – ...
Page 32
... OPEN PHASMD TG1 180° TG2 U1 LTC3729 90° CLKOUT 90° TG1 270° TG2 U2 LTC3828 90° PLLIN RELATED PARTS PART NUMBER DESCRIPTION LTC1628/LTC1628-PG/ 2-Phase, Dual Output Synchronous Step-Down LTC1628-SYNC DC/DC Controller LTC1629/ 20A to 200A PolyPhase LTC1629-PG LTC1702A No R 2-Phase Dual Synchronous Step-Down ...