ISL78235ARZ-T7A

DATASHEET ISL78235 FN8713 Rev 7.00 Sep 28, 2018 5A Automotive Synchronous Buck Regulator The ISL78235 is a highly efficient, monolithic, synchronous step-down DC/DC converter that can deliver 5A of continuous output current from a 2.7V to 5.5V input supply. The device uses peak current mode control architecture to achieve very low duty cycle operation at high frequency with fast transient response and excellent loop stability. The ISL78235 integrates a low ON-resistance P-channel (35mΩ, typical) high-side FET and N-channel (11mΩ, typical) low-side FET to maximize efficiency and minimize external component count. The 100% duty cycle operation allows less than 250mV dropout voltage at 5A output current. The operating frequency of the Pulse-Width Modulator (PWM) is adjustable from 500kHz to 4MHz. The default switching frequency of 2MHz is set by connecting the FS pin high. The ISL78235 can be configured for discontinuous (PFM) or forced continuous (PWM) operation at light load. Forced continuous operation reduces noise and RF interference; discontinuous mode provides higher efficiency by reducing switching losses at light loads. Fault protection is provided by internal hiccup mode current limiting during short-circuit and overcurrent conditions. The device also integrates output overvoltage and over-temperature protections. A power-good monitor indicates when the output is in regulation. The ISL78235 features a 1ms Power-Good (PG) timer at power-up. When in shutdown, the ISL78235 discharges the output capacitor through an internal 100Ω soft-stop switch. Other features include internal fixed or adjustable soft-start and internal/external compensation. The ISL78235 is available in a 3mmx3mm 16 Ld Thin Quad Flat No-lead (TQFN) Pb-free package and in a 5mmx5mm 16 Ld Wettable Flank Quad Flat No-Lead (WFQFN) package with an exposed pad for improved thermal performance. The ISL78235 is rated to operate across the temperature range of -40°C to +105°C in the 3mmx3mm package and -40°C to +125°C in the 5mmx5mm package. VIN 15 PHASE 14 11 *ISL78235 10 SYNC 4 9 8 COMP 7 SS 6 FS EN 5 • 100ns guaranteed phase minimum on time for wide output regulation • Adjustable switching frequency from 500kHz to 4MHz • External synchronization from 1MHz to 4MHz • Optional PFM mode for light-load efficiency improvement • Very low ON-resistance HS/LS switches: 35mΩ/11mΩ • Internal 1ms or adjustable external soft-start • Soft-stop output discharge during disable • OTP, OCP, output OVP, and input UVLO protections • 1% reference accuracy over-temperature • Up to 95% efficiency • AEC-Q100 qualified • Common pinout family allows migration from 3A to 5A without PCB change: - ISL78233 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3A - ISL78234 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4A - ISL78235 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5A Applications • DC/DC POL modules • μC/µP, FPGA, and DSP power • Video processor/SOC power • Automotive infotainment power Related Literature For a full list of related documents, visit our website - ISL78235 product page 100 5A LOAD DSP, FPGA 90 13 12 PG 3 • 2MHz default switching frequency COUT 1 VDD 2 VOUT • 2.7V to 5.5V input voltage range EFFICIENCY (%) 16 PHASE VIN CIN PHASE L 2.7V TO 5.5V Features PGND PGND SGND 2.5VOUT 80 3.3VOUT 1.8VOUT 1.5VOUT 70 1.2VOUT 60 FB 50 *Pin Compatible ISL78233 - 3A BUCK ISL78234 - 4A BUCK 40 TA = +25°C 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 OUTPUT LOAD (A) FIGURE 1. TYPICAL APPLICATION: 5A BUCK REGULATOR FN8713 Rev 7.00 Sep 28, 2018 FIGURE 2. EFFICIENCY vs LOAD (VIN = 5V; fsw = 2MHz; SYNC = GND) Page 1 of 24 ISL78235 Table of Contents Functional Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Pin Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Pin Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Typical Application Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Thermal Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Typical Operating Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Theory of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PWM Control Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Skip Mode (PFM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Frequency Adjust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Overcurrent Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Negative Current Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . UVLO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Soft Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Discharge Mode (Soft-Stop) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Power MOSFETs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100% Duty Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thermal Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 16 16 17 17 17 17 17 17 18 18 18 18 18 Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Output Inductor and Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Output Voltage Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Input Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Loop Compensation Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 18 18 19 19 PCB Layout Recommendation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Package Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 L16.3x3D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 L16.5x5D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 FN8713 Rev 7.00 Sep 28, 2018 Page 2 of 24 ISL78235 Functional Block Diagram COMP SS SHUTDOWN SYNC 55pF Soft SOFTSTART SHUTDOWN VDD 100kΩ + BANDGAP VREF + EN FS + COMP - EAMP - VIN OSCILLATOR PWM/PFM LOGIC CONTROLLER PROTECTION HS DRIVER 3pF + P PHASE LS DRIVER N PGND FB 6kΩ SLOPE Slope COMP 0.8V + CSA - + OV 0.85*VREF PG + UV + OCP - + SKIP - ISET THRESHOLD 1ms DELAY NEG CURRENT SENSING SGND ZERO-CROSS SENSING 0.5V SCP + 100Ω SHUTDOWN FIGURE 3. FUNCTIONAL BLOCK DIAGRAM FN8713 Rev 7.00 Sep 28, 2018 Page 3 of 24 ISL78235 Pin Configuration 16 15 14 PHASE PHASE PHASE VIN ISL78235 (16 LD TQFN, WFQFN) TOP VIEW 13 12 PGND VIN 1 11 PGND VDD 2 EPAD 10 SGND PG 3 9 5 6 7 8 EN FS SS COMP SYNC 4 FB Pin Descriptions PIN NUMBER PIN NAME 1, 16 VIN Input supply voltage. Place a minimum of two 22µF low ESR ceramic capacitors from VIN to PGND as close as possible to the IC for decoupling. DESCRIPTION 2 VDD Input supply voltage for the logic circuitry. A 0.1µF high frequency decoupling ceramic capacitor should also be placed close to the VDD and SGND pin. Connect to the VIN pin. 3 PG PG is an open-drain output for power-good indication. Use a 10kΩ to 100kΩ pull-up resistor connected from PG to VIN. At power-up or EN high, the PG rising edge is delayed by 1ms upon output voltage within regulation. 4 SYNC Mode selection pin. Connect to logic high or input voltage VIN for forced PWM mode. Connect to logic low or ground for PFM mode. Connect to an external function generator for synchronization with a positive edge trigger. In external synchronization the ISL78235 operates in forced PWM mode. The transition to and from the internal oscillator to external synchronization is seamless and does not require disabling the ISL78235. An internal 1MΩ pull-down resistor to SGND prevents an undefined logic state if the SYNC pin is floating. 5 EN Regulator enable pin. The regulator is enabled when driven logic high. The regulator is shut down and the PHASE pin discharges the output capacitor when the enable pin is driven low. 6 FS This pin sets the internal oscillator switching frequency using a resistor, RFS, from the FS pin to GND. The frequency of operation may be programmed between 500kHz to 4MHz. The switching frequency is 2MHz if FS is connected to VIN. 7 SS SS is used to adjust the soft-start time. Connect the SS pin to SGND for an internal 1ms soft-start time. Connect a capacitor from SS to SGND to adjust the soft-start time. Do not use more than 33nF on the SS pin. 8 COMP COMP is the output of the error amplifier if COMP is not connected to VDD. An external compensation network must be used if COMP is not tied to VDD. If COMP is tied to VDD, the error amplifier output is internally compensated. External compensation network across COMP and SGND may be required to improve the loop compensation of the amplifier. 9 FB The feedback network of the regulator, FB, is the negative input to the transconductance error amplifier. The output voltage is set by an external resistor divider connected to FB. With a properly selected divider, the output voltage can be set to any voltage between the power rail (reduced by converter losses) and the 0.6V reference. In addition, the regulator power-good and undervoltage protection circuitry use FB to monitor the regulator output voltage. 10 SGND Signal ground. Connect to PGND. 11, 12 PGND Power ground. 13, 14, 15 PHASE Switching node connections. Connect to one terminal of the inductor. This pin is discharged by a 100Ω resistor when the device is disabled. See “Functional Block Diagram” on page 3 for more detail. Exposed Pad EPAD The exposed pad must be connected to the SGND pin for proper electrical performance. Place as many vias as possible under the pad connecting to SGND plane for optimal thermal performance. FN8713 Rev 7.00 Sep 28, 2018 Page 4 of 24 ISL78235 Ordering Information PART NUMBER (Note 4) PART MARKING OUTPUT VOLTAGE (V) TEMP. RANGE (°C) TAPE AND REEL (UNITS) PACKAGE (RoHS Compliant) PKG. DWG. # ISL78235ARZ (Note 2) 8235 Adjustable -40°C to +105°C - 16 Ld 3x3mm TQFN L16.3x3D ISL78235ARZ-T (Notes 1, 2) 8235 Adjustable -40°C to +105°C 6k 16 Ld 3x3mm TQFN L16.3x3D ISL78235ARZ-T7A (Notes 1, 2) 8235 Adjustable -40°C to +105°C 250 16 Ld 3x3mm TQFN L16.3x3D ISL78235AARZ (Note 3) 78235A ARZ Adjustable -40°C to +125°C - 16 Ld 5x5mm WFQFN L16.5x5D ISL78235AARZ-T (Notes 1, 3) 78235A ARZ Adjustable -40°C to +125°C 6k 16 Ld 5x5mm WFQFN L16.5x5D ISL78235AARZ-T7A (Notes 1, 3) 78235A ARZ Adjustable -40°C to +125°C 250 16 Ld 5x5mm WFQFN L16.5x5D ISL78235EVAL1Z 3x3mm TQFN Evaluation Board ISL78235EVAL2Z 5x5mm WFQFN Evaluation Board NOTES: 1. Refer to TB347 for details about reel specifications. 2. These Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials and 100% matte tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020. 3. These Pb-free Hermetic packaged products employ 100% Au plate - e4 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations. 4. For Moisture Sensitivity Level (MSL), refer to the ISL78235 product information page. For more information about MSL, refer to TB363. TABLE 1. KEY DIFFERENCE BETWEEN FAMILY OF PARTS FN8713 Rev 7.00 Sep 28, 2018 PART NUMBER IOUT MAX (A) ISL78235 5 ISL78234 4 ISL78233 3 Page 5 of 24 ISL78235 Typical Application Diagram / ȝ+ 9729 9$ 9,1 32:(5*22' ,1',&$725   (;7(51$/ 6