LT8648S (Rev. A) - Analog Devices

1 LT8648S . 42V, 15A Synchronous step - down Silent Switcher 2. FEATURES DESCRIPTION. n Silent Switcher 2 Architecture The LT 8648S synchronous step - down regulator n ultralow EMI Emissions on Any PCB features second generation Silent Switcher architecture n Eliminates PCB Layout Sensitivity designed to minimize EMI emissions while delivering high n Internal Bypass Capacitors Reduce Radiated EMI efficiency at high switching frequencies. This includes n Optional Spread Spectrum Modulation the integration of input and boost capacitors to optimize n high efficiency at high Frequency all the fast current loops inside and make it easy to n Up to efficiency at 1 MHz, 12V to 5V. IN OUT. achieve advertised EMI performance by reducing layout n Up to 93% efficiency at 2 MHz, 12V to 5V. IN OUT. sensitivity. This performance makes the LT8648S ideal for n Wide Input Voltage Range: 3V to 42V noise sensitive applications and environments. n 15A Output Current The fast, clean, low overshoot switching edges enable high n Low Quiescent Current Burst Mode Operation efficiency operation even at high switching frequencies, n 100 A I Regulating 12V to 5V leading to a small overall solution size.

2 Peak current mode Q IN OUT. n Output Ripple < 10mV control with a 25ns minimum on-time allows high step P-P. n External Compensation: Fast Transient Response and down ratios even at high switching frequencies. External Current Sharing compensation via the VC pin allows for fast transient n Fast Minimum Switch On-Time: 25ns response at high switching frequencies. The VC pin n Low Dropout Under All Conditions: 35mV at 1A also enables current sharing and a CLKOUT pin enables n Forced Continuous Mode synchronizing other regulators to the LT8648S . n Adjustable and Synchronizable: 200kHz to Burst Mode operation enables low standby current n Output Soft-Start and Power Good consumption, forced continuous mode can control n Safely Tolerates high Reverse Current frequency harmonics across the entire output load n Small 36-Lead 7mm 4mm LQFN Package range, or spread spectrum operation can further reduce n AEC-Q100 Qualified for Automotive Applications EMI emissions.

3 Soft-start and tracking functionality is accessed via the SS pin, and an accurate input voltage APPLICATIONS UVLO threshold can be set using the EN/UV pin. n Automotive and Industrial Supplies All registered trademarks and trademarks are the property of their respective owners. Protected by patents, including 8823345. n General Purpose step - down TYPICAL APPLICATION 12V to 5V. 12 VIN to 5 VOUT efficiency OUTE fficiency 100 8. 5V 15A step - down Converter 95 7. VIN 90 efficiency 6. TO 42V VIN. POWER LOSS (W). efficiency (%). 10 F 85 5. EN/UV 1 H VOUT. SW 5V 80 4. 15A POWER LOSS. INTVCC BIAS 75 3. 1 F LT8648S 10pF 100k 70 2. VC. 47 F 400kHz, L = H. RT FB 65 1. x2 1 MHz, L = 1 H. 330pF. GND 2 MHz, L = H. 60 0. 1 3 5 7 9 11 13 15. fSW = 1 MHz 8648S TA01a LOAD CURRENT (A) 8648S TA01b Rev. A. Document Feedback For more information 1. LT8648S . ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION. (Note 1) TOP VIEW. VIN, EN/UV, SYNC/MODE. CLKOUT. FB, SS ..4V. PG.

4 SS. VC. FB. SYNC/MODE Voltage ..6V 36 35 34 33 32 31. Operating Junction Temperature Range (Note 2) BIAS 1 30 RT. 40 C to 125 C INTVCC 2. 37 38. 29 EN/UV. 40 C to 150 C BST 3 GND GND 28 VIN. 40 C to 150 C SW 4 27 VIN. Storage Temperature 65 C to 150 C SW 5 26 VIN. Maximum Reflow (Package Body) 260 C SW 6 39 40 25 NC. GND GND. SW 7 24 GND. SW 8 23 GND. SW 9 22 NC. SW 10 41 42 21 VIN. GND GND. SW 11 20 VIN. SW 12 19 VIN. 13 14 15 16 17 18. GND. GND. GND. GND. GND. GND. LQFN PACKAGE. 36-LEAD (7mm 4mm ). JEDEC BOARD: JA = 26 C/W, JT = C/W, JCTOP = C/W, JCBOT = C/W (Note 3). DEMO BOARD: JA = 15 C/W. EXPOSED PAD (PINS 37-42) ARE GND, SHOULD BE SOLDERED TO PCB. ORDER INFORMATION. PACKAGE MSL. PART NUMBER PART MARKING* FINISH CODE PAD FINISH TYPE** RATING TEMPERATURE RANGE. LT8648 SEV#PBF 40 C to 125 C. LQFN (Laminate Package LT8648 SJV#PBF 8648S e4 Au (RoHS) 3. with QFN Footprint) 40 C to 150 C. LT8648 SHV#PBF. AUTOMOTIVE PARTS**. LT8648 SEV#WPBF 40 C to 125 C.

5 LQFN (Laminate Package LT8648 SJV#WPBF 8648S e4 Au (RoHS) 3. with QFN Footprint) 40 C to 150 C. LT8648 SHV#WPBF. Contact the factory for parts specified with wider operating temperature Recommended LGA and BGA PCB Assembly and Manufacturing ranges. *Pad or ball finish code is per IPC/JEDEC J-STD-609. Procedures LGA and BGA Package and Tray Drawings Parts ending with PBF are RoHS and WEEE compliant. **The LT8648S package has the same dimensions as a standard 7mm 4mm QFN package. **Versions of this part are available with controlled manufacturing to support the quality and reliability requirements of automotive applications. These models are designated with a #W suffix. Only the automotive grade products shown are available for use in automotive applications. Contact your local Analog Devices account representative for specific product ordering information and to obtain the specific Automotive Reliability reports for these models. Rev. A. 2 For more information LT8648S .

6 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25 C. PARAMETER CONDITIONS MIN TYP MAX UNITS. Minimum Input Voltage fSW = 400kHz V. fSW = 2 MHz l V. VIN Quiescent Current in Shutdown VEN/UV = 0V, VIN = 12V 6 9 A. VIN Quiescent Current in Sleep VEN/UV = 2V, VFB > , VSYNC = 0V, VBIAS = 0V 140 195 A. l 140 255 A. VEN/UV = 2V, VFB > , VSYNC = 0V, VBIAS = 5V 20 29 A. BIAS Quiescent Current in Sleep VEN/UV = 2V, VFB > , VSYNC = 0V, VBIAS = 5V 100 145 A. Feedback Reference Voltage VIN = 12V V. VIN = 12V l V. Feedback Voltage Line Regulation VIN = to 40V, VC = l %/V. Feedback Pin Input Current VFB = 20 20 nA. Error Amp Transconductance VC = mS. Error Amp Gain 600 V/V. VC Source Current VFB = , VC = 320 A. VC Sink Current VFB = , VC = 320 A. VC Pin to Switch Current Gain 18 A/V. VC Clamp Voltage V. BIAS Pin Current Consumption VBIAS = , fSW = 2 MHz, VIN = 12V 60 mA.

7 Minimum On-Time ILOAD = 3A, SYNC = 2V l 25 40 ns Minimum Off-Time 75 100 ns Oscillator Frequency RT = 226k l 170 200 230 kHz RT = l 1 MHz RT = l 2 MHz Top Power NMOS On-Resistance ISW = 1A 12 m . Top Power NMOS Current Limit l 24 30 34 A. Bottom Power NMOS On-Resistance VINTVCC = , ISW = 1A m . Bottom Power NMOS Current Limit VINTVCC = 15 21 27 A. SW Leakage Current VIN = 42V, VSW = 0V, 42V A. EN/UV Pin Threshold EN/UV Rising l V. EN/UV Pin Hysteresis 40 mV. EN/UV Pin Current VEN/UV = 2V 20 20 nA. PG Upper Threshold Offset from VFB VFB Rising l 6 %. PG Lower Threshold Offset from VFB VFB Falling l 6 %. PG Hysteresis %. PG Leakage VPG = 80 80 nA. PG Pull- down Resistance VPG = l 600 2000 . SYNC/MODE Threshold SYNC/MODE DC and Clock Low Level Voltage l V. SYNC/MODE Clock high Level Voltage l V. SYNC/MODE DC high Level Voltage l V. Spread Spectrum Modulation RT = 24 %. Frequency Range Rev. A. For more information 3. LT8648S . ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25 C.

8 PARAMETER CONDITIONS MIN TYP MAX UNITS. Spread Spectrum Modulation Frequency 3 kHz SS Source Current l A. SS Pull- down Resistance Fault Condition, SS = 200 . VIN to Disable Forced Continuous Mode VIN Rising 35 40 V. Note 1: Stresses beyond those listed under Absolute Maximum Ratings Note 3: values determined per JEDEC 51-7, 51-12. See the Applications may cause permanent damage to the device. Exposure to any Absolute Information section for information on improving the thermal resistance Maximum Rating condition for extended periods may affect device and for actual temperature measurements of a demo board in typical reliability and lifetime. operating conditions. Note 2: The LT8648SE is guaranteed to meet performance specifications Note 4: This IC includes overtemperature protection that is intended to from 0 C to 125 C junction temperature. Specifications over the 40 C protect the device during overload conditions. Junction temperature will to 125 C operating junction temperature range are assured by design, exceed 150 C when overtemperature protection is active.

9 Continuous characterization, and correlation with statistical process controls. The operation above the specified maximum operating junction temperature LT8648SJ and LT8648SH are guaranteed over the full 40 C to 150 C will reduce lifetime. operating junction temperature range. high junction temperatures degrade operating lifetimes. Operating lifetime is derated at junction temperatures greater than 125 C. The junction temperature (TJ, in C) is calculated from the ambient temperature (TA in C) and power dissipation (PD, in Watts). according to the formula: TJ = TA + (PD JA). where JA (in C/W) is the package thermal impedance. Rev. A. 4 For more information LT8648S . TYPICAL PERFORMANCE CHARACTERISTICS. to 5V. 12 VIN to 5 VOUT efficiency OUT efficiency 12 VIN to efficiency OUT efficiency Frequency vs Frequency vs Frequency Frequency efficiency efficiency at 5V. 5 Vout OUT. 100 8 100 8 100 8. FC MODE FC MODE FC MODE. 95 7 95 7 95 7. 90 efficiency 6 90 6 90 6.

10 efficiency . POWER LOSS (W). POWER LOSS (W). POWER LOSS (W). efficiency (%). efficiency (%). efficiency (%). 85 5 85 5 85 5. 80 4 80 4 80 4. POWER LOSS POWER LOSS. 75 3 75 3 75 3. 70 L = XAL8080 2 70 L = XAL8080 2 70 VIN = 12V 2. 400kHz, L = H 400kHz, L = VIN = 24V. 65 1 MHz, L = 1 H 1 65 1 MHz, L = 1uH 1 65 VIN = 36V 1. 2 MHz, L = H 2 MHz, L = fSW = 400kHz, L = XAL8080, H. 60 0 60 0 60 0. 1 3 5 7 9 11 13 15 1 3 5 7 9 11 13 15 1 3 5 7 9 11 13 15. LOAD CURRENT (A) LOAD CURRENT (A) LOAD CURRENT (A). 8648S G01 8648S G02 8648S G03. efficiency at efficiency Low Load efficiency Efficiencyatat5V. 5 VOUT. OUT LowLoad Low LoadEfficiency OUT. 100 8 100 100. FC MODE. 95 7 90 90. 80 80. 90 6. 70 70. POWER LOSS (W). efficiency (%). efficiency (%). efficiency (%). 85 5. 60 60. 80 4. 50 50. 75 3 VIN = 12V VIN = 12V. 40 40 VIN = 24V. VIN = 24V. 70 VIN = 12V 2 VIN = 36V VIN = 36V. 30 30. VIN = 24V fSW = 400kHz fSW = 400kHz 65 VIN = 36V 1 20 L = XAL8080, 20 L = XAL8080, H.