AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming General Description Features The AAT1210 is a high power DC/DC boost (step-up) converter with an input voltage range from 2.7 to 5.5V. The output voltage can be set from VIN + 0.5V to 18V. The total solution is less than 1mm in height. High operating efficiency makes the AAT1210 the ideal solution for battery powered and consumer applications. • • The step-up converter operates at frequencies up to 2MHz, enabling ultra-small external filtering components. Hysteretic current mode control provides excellent transient response with no external compensation, achieving stability across a wide operating range with minimal design effort. The AAT1210 true load disconnect feature extends battery life by isolating the load from the power source when the EN/SET pin is pulled low, ensuring zero volts output during the disable state. This feature eliminates the external boost converter leakage path and achieves standby quiescient current <1µA without an external switching device. A fixed output voltage is set using two external resistors. Alternatively, the output may be adjusted dynamically across a 2.0x range. The output can toggle between two preset voltages using the SEL logic pin. Optionally, the output can be dynamically set to any one of 16 programmed levels using AnalogicTech's patented Simple Serial Control™ (S2Cwire™) interface. The AAT1210 is available in a Pb-free, thermallyenhanced 16-pin 3x4mm TDFN low-profile package and is rated over the -40°C to +85°C temperature range. • • • • • • • • • • • • SwitchReg™ VIN Range: 2.7V to 5.5V Maximum Continuous Output — 900mA at 5V — 300mA at 12V — 150mA at 18V Up to 2MHz Switching Frequency Ultra-Small Inductor and Capacitors — 1mm Height Inductor — Small Ceramic Capacitors Hysteretic Current Mode Control — No External Compensation — Excellent Transient Response — High Efficiency at Light Load Up to 90% Efficiency Integrated Low RDS(ON) MOSFET Switches Low Inrush with Integrated Soft Start Cycle-by-Cycle Current Limit Short-Circuit and Over-Temperature Protection True Load Disconnect Optional Dynamic Voltage Programming TDFN34-16 Package -40°C to +85°C Temperature Range Applications • • • • • • GPS Systems DVD Blu-Ray Handheld PCs PDA Phones Portable Media Players USB OTG Typical Application VIN 3.6V VOUT 5V @ 900mA L1 0.47µH AAT1210 TDFN34-16 AAT1210 Boost Converter Output Capability (TDFN34-16; TAMB = 25°°C; TC(RISE) = +50°C) D1 EN/SET SW SEL FB1 GND C1 4.7µF 0603 LIN FB2 R3 4.99kΩ R2 40.2kΩ C2 10µF 0603 Output Current (mA) VIN 1400 7 VIN = 4.5V 1200 1000 VIN = 3.6V 800 VIN = 2.7V 600 400 200 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Output Voltage (V) 1210.2007.02.1.2 1 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Pin Descriptions Pin # Symbol 1, 2 3 LIN FB1 4 FB2 5 6, 7, 8 GND PGND 9, 10 SW 11 12 13 N/C VIN SEL 14 15, 16 EN/SET VP EP Function Switched power input. Connect to the power inductor. Feedback pin for high output voltage set point. Pin set to 1.2V when SEL is high and disabled when SEL is low. Disabled with S2Cwire control. Tie directly to FB2 pin for static (fixed) output voltage. Feedback pin for low output voltage set point. Pin set to 0.6V when SEL is low and disabled when SEL is high. Voltage is set from 0.6V to 1.2V with S2Cwire control. Tie directly to FB1 pin for static (fixed) output voltage. Ground pin. Power ground for the boost converter; connected to the source of the N-channel MOSFET. Connect to the input and output capacitor return. Boost converter switching node. Connect the power inductor between this pin and the LIN pin. No connection. Input voltage for the converter. Connect this pin directly to the VP pin. Logic high selects FB1 high output reference. Logic low selects FB2 low output reference. Pull low for S2Cwire control. Active high enable pin. Alternately, input pin for S2Cwire control using the FB2 reference. Input power pin; connected internally to the source of the P-channel MOSFET. Connect externally to the input capacitor(s). Exposed paddle (bottom). Connected internally to the SW pins. Can be tied to bottom side PCB heat sink to optimize thermal performance. Pin Configuration TDFN34-16 (Top View) LIN LIN FB1 FB2 GND PGND PGND PGND 2 1 16 2 15 3 14 4 13 5 12 6 11 7 10 8 9 VP VP EN/SET SEL VIN N/C SW SW 1210.2007.02.1.2 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Absolute Maximum Ratings1 Symbol VIN, VP SW LIN, EN/SET, SEL, FB1, FB2 TJ TS TLEAD Description Value Units Input Voltage Switching Node -0.3 to 6.0 20 V V Maximum Rating VIN + 0.3 V -40 to 150 -65 to 150 300 °C °C °C Value Units 44 2270 °C/W mW Operating Temperature Range Storage Temperature Range Maximum Soldering Temperature (at leads, 10 sec) Recommended Operating Conditions Symbol θJA PD Description Thermal Resistance Maximum Power Dissipation (TA = 25ºC) 1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time. 1210.2007.02.1.2 3 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Electrical Characteristics1 VIN = 3.6V, TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol Power Supply VIN VOUT IOUT(MAX) VUVLO IQ Description Conditions Input Voltage Range Output Current UVLO Threshold Quiescent Current ISHDN VIN Pin Shutdown Current FB1 FB1 Reference Voltage FB2 FB2 Reference Voltage ΔVLOADREG ΔVLINEREG/ΔVIN Load Regulation Line Regulation Low Side Switch On Resistance Input Disconnect Switch On Resistance RDS(ON)L RDS(ON)IN TSS TSD THYS ILIM Soft-Start Time Over-Temperature Shutdown Threshold Shutdown Hysteresis N-Channel Current Limit Typ 2.7 VIN + 0.5V Output Voltage Range 2 Min VIN = 2.7V, VOUT = 5V VIN = 2.7V, VOUT > 5V VIN = 3.6V, VOUT > 5V VIN Rising Hysteresis VIN Falling SEL = GND, VOUT = 5V, No Load, Switching3 SEL = GND, FB2 = 1.5V, Not Switching EN/SET = GND IOUT = 0 to IOUT(MAX) mA, VIN = 2.7V to 5.0V, SEL = High IOUT = 0 to IOUT(MAX) mA, VIN = 2.7V to 5.0V, SEL = Low IOUT = 0 to IOUT(MAX) mA VIN = 3.0V to 5.5V Units 5.5 V 18 V 600 See note 2 900 mA 2.7 150 V mV V 250 µA 1.8 40 70 µA 1.0 µA 1.164 1.2 1.236 V 0.582 0.6 0.618 V From Enable to Output Regulation; VOUT = 15V , COUT = 10µF VIN = 3.6V , L =2.2µH Max 3.0 0.01 0.6 %/mA %/V 0.06 Ω 0.18 Ω 2.5 ms 140 °C 15 °C A 1. Specifications over the -40°C to +85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. 2. Maximum output power and current is dependent upon operating efficiency and thermal/mechanical design. Output current and output power derating may apply. See Figure 1. 3. Total input current with prescribed FB resistor network can be reduced with larger resistor values. 4 1210.2007.02.1.2 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Electrical Characteristics1 VIN = 3.6V, TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol SEL, EN/SET VSEL(L) VSEL(H) VEN/SET(L) VEN/SET(H) TEN/SET LO TEN/SET HI MIN TEN/SET HI MAX TOFF TLAT IEN/SET Description Conditions SEL Threshold Low SEL Threshold High Enable Threshold Low Enable Threshold High EN/SET Low Time Minimum EN/SET High Time Maximum EN/SET High Time EN/SET Off Timeout EN/SET Latch Timeout EN/SET Input Leakage VIN VIN VIN VIN = = = = 2.7V 5.5V 2.7V 5.5V Min Typ Max Units 0.4 V V V V µs ns µs µs µs µA 1.4 0.4 1.4 0.3 75 50 -1 75 500 500 1 1. Specifications over the -40°C to +85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. 1210.2007.02.1.2 5 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Typical Characteristics Efficiency vs. Load DC Regulation (VOUT = 5V) (VOUT = 5V) 95 2 75 VIN = 4.2V 65 VIN = 4.5V 1 VIN = 3.6V VIN = 4.5V 55 45 Output Error (%) Efficiency (%) 85 0 -1 VIN = 4.2V VIN = 3.6V VIN = 3.0V VIN = 2.7V -2 -3 -4 35 -5 25 0.1 1 10 100 0.1 1000 1 10 Output Current (mA) DC Regulation (VOUT = 9V) 75 65 VIN = 3.6V 55 VIN = 5.5V 1 VIN = 4.2V 45 VIN = 4.5V Output Error (%) Efficiency (%) (VOUT = 9V) 2 VIN = 5.5V 85 35 25 -1 -2 VIN = 4.2V -3 VIN = 3.6V VIN = 3.0V VIN = 2.7V -5 1 10 100 0.1 1000 1 Output Current (mA) DC Regulation (VOUT = 12V) Efficiency (%) 2 VIN = 4.5V 75 VIN = 3.6V 65 VIN = 4.2V 55 VIN = 5.5V 1 45 Output Error (%) VIN = 5.5V 0 10 Output Current (mA) 100 1000 VIN = 3.6V -2 VIN = 3.0V -3 -5 0.1 VIN = 4.5V VIN = 4.2V -1 VIN = 2.7V -4 1 1000 Output Current (mA) 35 6 100 (VOUT = 12V) 85 25 0.1 10 Efficiency vs. Load 95 VIN = 4.5V 0 -4 0.1 1000 Output Current (mA) Efficiency vs. Load 95 100 1 10 100 1000 Output Current (mA) 1210.2007.02.1.2 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Typical Characteristics Efficiency vs. Load DC Regulation (VOUT = 15V) (VOUT = 15V) 2 95 75 65 VIN = 3.6V 55 VIN = 4.2V 45 0 VIN = 4.2V -1 VIN = 3.6V -2 VIN = 3.0V -3 VIN = 2.7V -4 35 25 0.1 1 10 100 -5 0.1 1000 1 Output Current (mA) 0.4 Output Error (%) Accuracy (%) (VIN = 3.6V; VOUT = 12V; IOUT = 100mA) VIN = 5.5V 0.5 VIN = 2.7V 0 -0.5 VIN = 3.6V -1 VIN = 3.0V -1.5 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -2 2.5 3 3.5 4 4.5 5 5.5 -0.5 -40 6 -15 35 60 No Load Input Current vs. Input Voltage No Load Input Current vs. Temperature (EN = High) (VIN = 3.6V; VOUT = 5V) 85 0.34 2.5 Supply Current (mA) 3 Supply Current (mA) 10 Temperature (°°C) Input Voltage (V) VOUT = 18V 2 1.5 1000 0.5 VIN = 4.2V 1 100 Output Voltage Error vs. Temperature (VOUT = 12V) 1.5 10 Output Current (mA) Line Regulation 2 VIN = 4.5V VIN = 5.5V 1 Output Error (%) Efficiency (%) VIN = 4.5V VIN = 5.5V 85 VOUT = 9V 1 VOUT = 12V VOUT = 5V 0.5 0 2.5 3 3.5 4 4.5 Input Voltage (V) 1210.2007.02.1.2 5 5.5 6 0.33 0.32 0.31 0.3 0.29 0.28 0.27 0.26 0.25 -40 -15 10 35 60 85 Temperature (°°C) 7 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Typical Characteristics AC Output Ripple vs. Output Current Output Ripple (VOUT = 9V) (VIN = 3.6V; VOUT = 15V; IOUT = 150mA; L = 1.2µH) VIN = 2.7V 50 VIN = 3.0V Output Voltage (top) (V) 60 VIN = 5.5V 40 VIN = 3.6V 30 VIN = 4.2V 20 10 0 0 50 100 150 200 250 15.1 12 15.05 10 15 8 14.95 6 14.9 4 14.85 2 14.8 0 14.75 -2 14.7 -4 300 Time (500ns/div) Output Current (mA) Output Ripple Load Transient Response (VIN = 3.6V; VOUT = 15V; No Load; L = 1.2µH) (VIN = 3.6V; VOUT = 5V; IOUT = 0mA to 600mA) 3.5 2.5 14.95 2 14.9 1.5 14.85 1 14.8 14.7 5.2 7 5 6 4.8 4.6 4.4 2 1 0 3.8 0 -0.5 3.6 -1 Time (20µs/div) Load Transient Response (VIN = 3.6V; VOUT = 12V; IOUT = 0mA to 200mA) 4.95 5 4.9 4.85 360mA 120mA 4 3 4.8 2 4.75 1 4.7 0 4.65 -1 Time (20µs/div) 12.4 7 12.2 6 12 5 11.8 4 11.6 11.4 200mA 0mA 3 2 11.2 1 11 0 10.8 -1 Output Current (A) (middle) Inductor Current (A) (bottom) 6 Output Current (A) (middle) Inductor Current (A) (bottom) 7 5 Output Voltage (top) (V) Load Transient Response (VIN = 3.6V; VOUT = 5V; IOUT = 120mA to 360mA) 5.05 Output Voltage (top) (V) 4 3 0mA 4 Time (200ns/div) 8 5 600mA 4.2 0.5 14.75 Output Voltage (top) (V) 15 Inductor Current (bottom) (A) Output Voltage (top) (V) 3 Output Current (A) (middle) Inductor Current (A) (bottom) 15.1 15.05 Inductor Current (bottom) (A) Output Voltage (mV) 70 Time (20µs/div) 1210.2007.02.1.2 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Load Transient Response Line Response (VIN = 3.6V; VOUT = 12V; IOUT = 40 to 120mA) (VOUT = 15V @ 100mA) 6 12 5 11.8 4 120mA 11.6 11.4 3 2 40mA 11.2 1 11 0 10.8 -1 Output Voltage (top) (V) 7 12.2 15.5 7.2 15.25 6.6 6 15 14.75 5.4 14.5 4.8 14.25 4.2 14 3.6 13.75 Input Voltage (bottom) (V) 12.4 Output Current (middle) (A) Inductor Current (bottom) (A) Output Voltage (top) (V) Typical Characteristics 3 13.5 2.4 Time (20µs/div) Time (100µs/div) Line Response P-Channel RDS(ON) vs. Input Voltage 5.4 7.2 300 5.2 6.6 280 6 4.8 5.4 4.6 4.8 4.4 4.2 4.2 3.6 4 100°C 240 220 200 180 160 25°C 140 3 3.8 120°C 260 RDS(ON) (mΩ Ω) 5 Input Voltage (bottom) (V) Output Voltage (top) (V) (VOUT = 5V @ 100mA) 85°C 120 100 2.4 2.5 3 Time (100µs/div) 3.5 4 4.5 5 5.5 6 Input Voltage (V) Soft Start N-Channel RDS(ON) vs. Input Voltage (VIN = 3.6V; CIN = 2.2µF; IOUT = 100mA; VOUT = 15V) 120°C 90 100°C 80 70 60 85°C 25°C 50 40 2.5 3 3.5 4 4.5 Input Voltage (V) 1210.2007.02.1.2 5 5.5 6 20 3.5 15 3 10 2.5 1.04V 5 2 0 1.5 -5 1 -10 0.5 -15 0 -20 -0.5 Input Current (bottom) (A) RDS(ON) (mΩ Ω) 100 Enable Voltage (middle) (V) Output Voltage (top) (V) 110 Time (500µs/div) 9 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Typical Characteristics Soft Start 8 1.75 6 1.5 4 1.25 1.04V 2 1 0 0.75 -2 0.5 -4 0.25 -6 0 -8 -0.25 Input Current (bottom) (A) Output Voltage (top) (V) Enable Voltage (middle) (V) (VIN = 3.6V; CIN = 2.2µF; IOUT = 100mA; VOUT = 5V) Time (500µs/div) 10 1210.2007.02.1.2 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Functional Block Diagram VIN LIN VP Soft-Start Timer EN/SET SW Control FB1 VREF1 Output Select VREF2 FB2 SEL GND Functional Description The AAT1210 consists of a DC/DC boost (step-up) controller, an integrated slew rate controlled input disconnect MOSFET switch, and a MOSFET power switch. A high voltage rectifier, power inductor, capacitors and resistor divider network are required to implement a DC/DC boost converter. The minimum output voltage must be 0.5V above the input voltage and the maximum output voltage is 18V. The operating input voltage range is 2.7V to 5.5V. Control Loop The AAT1210 provides the benefits of current mode control with a simple hysteretic feedback loop. The device maintains exceptional DC regulation, transient response, and cycle-by-cycle current limit without additional compensation components. The AAT1210 modulates the power MOSFET switching current in response to changes in output 1210.2007.02.1.2 PGND voltage. This allows the voltage loop to directly program the required inductor current in response to changes in the output load. The switching cycle initiates when the N-channel MOSFET is turned ON and current ramps up in the inductor. The ON interval is terminated when the inductor current reaches the programmed peak current level. During the OFF interval, the input current decays until the lower threshold, or zero inductor current, is reached. The lower current is equal to the peak current minus a preset hysteresis threshold, which determines the inductor ripple current. The peak current is adjusted by the controller until the output current requirement is met. The magnitude of the feedback error signal determines the average input current. The AAT1210 controller implements a programmed current source connected to the output capacitor and load resistor. There is no right-half plane zero, and loop stability is achieved with no additional compensation components. 11 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Increased load current results in a drop in the output feedback voltage (FB1 or FB2) sensed through the feedback resistors (R1, R2, R3 in Figure 2). The controller responds by increasing the peak inductor current, resulting in higher average current in the inductor. Alternatively, decreased output load results in an increase in the output feedback voltage. The controller responds by decreasing the peak inductor current, resulting in lower average current in the inductor. At light load, the inductor OFF interval current goes below zero, which terminates the off period, and the boost converter enters discontinuous mode operation. Further reduction in the load results in a corresponding reduction in the switching frequency. The AAT1210 provides optimized light load operation which reduces switching losses and maintains the highest possible efficiency at light load. The AAT1210 switching frequency varies with changes in the input voltage, output voltage, and inductor size. Once the boost converter has reached continuous mode, further increases in the output load will not significantly change the operating frequency and constant ripple current in the boost inductor is maintained. Output Voltage Programming The FB reference voltage is determined by the logic state of the SEL pin. The output voltage is programmed through a resistor divider network (R1, R2, R3) from the positive output terminal to FB1/FB2 pins to ground. Pulling the SEL pin high activates the FB1 pin which maintains a 1.2V reference voltage, while the FB2 reference is disabled. Pulling the SEL pin low activates the FB2 pin which maintains a 0.6V reference, while the FB1 reference is disabled. The FB1 and FB2 pins may be tied together when a static DC output voltage is desired. Toggling the SEL pin programs the output voltage between two distinct output voltages across a 2.0X range (maximum). With FB1, FB2 tied together, the output voltage toggles between two voltages with a 2.0X scaling factor. An additional resistor between FB1 and FB2 pins allows toggling between two voltages with a <2.0X scaling factor. 12 Alternatively, the output voltage may be dynamically programmed to any of 16 voltage levels using the S2Cwire serial digital input. The single-wire S2Cwire interface provides high-speed output voltage programmability across a 2.0X output voltage range. S2Cwire functionality is enabled by pulling the SEL pin low and providing S2Cwire digital clock input to the EN/SET pin which sets the FB2 voltage level from 0.6V to 1.2V. Table 6 details the FB2 reference voltage versus S2Cwire rising clock edges. Soft Start / Enable The input disconnect switch is activated when a valid input voltage is present and the EN/SET pin is pulled high. The slew rate control on the P-channel MOSFET ensures minimal inrush current as the output voltage is charged to the input voltage, prior to switching of the N-channel power MOSFET. Monotonic turn-on is guaranteed by the integrated soft-start circuitry. Soft-start time of approximately 2.5ms is internally programmed to minimize inrush current and eliminate output voltage overshoot across the full input voltage range under all loading conditions. Current Limit and Over-Temperature Protection The switching of the N-channel MOSFET terminates if the current limit of 3.0A (minimum) is exceeded. This minimizes power dissipation and component stresses under overload and short-circuit conditions. Switching resumes when the current decays below the current limit. Thermal protection disables the AAT1210 if internal power dissipation becomes excessive. Thermal protection disables both the N-channel and P-channel MOSFETs. The junction over-temperature threshold is 140°C with 15°C of hysteresis. The output voltage automatically recovers when the over-temperature or over-current fault condition is removed. Under-Voltage Lockout Internal bias of all circuits is controlled via the VIN input. Under-voltage lockout (UVLO) guarantees sufficient VIN bias and proper operation of all internal circuitry prior to activation. 1210.2007.02.1.2 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Applications Information with plated through vias. Details of the PCB layout are provided in Figures 6, 7, and 8. Output Current and Power Capability Actual case temperature may vary and depends on the boost converter efficiency and the system thermal design; including, but not limited to airflow, local heat sources, etc. Additional derating may apply. The AAT1210 boost converter provides a high voltage, high current, regulated DC output voltage from a low voltage DC input. The operating input voltage range is 2.7 to 5.5V. Selecting the Output Diode Figure 1 details the output current and power capability of the AAT1210 for output voltages from 5V to 18V with DC input of 2.7V, 3.6V and 4.5V. The maximum output current/power curves are based on +50ºC case temperature rise over ambient using the TDFN34-16 package. Ambient temperature at 25ºC, natural convection is assumed. Up to 1.3A of output current is possible with 4.5V input voltage. As shown in Figure 1, the output capability is somewhat reduced at higher output voltage and reduced input voltage. To ensure minimum forward voltage drop and no recovery, a high voltage Schottky diode is considered the best choice for use with the AAT1210 boost converter. The AAT1210 output diode is sized to maintain acceptable efficiency and reasonable operating junction temperature under full load operating conditions. Forward voltage (VF) and package thermal resistance (θJA) are the dominant factors to consider in selecting a diode. The diode's published current rating may not reflect actual operating conditions and should be used only as a comparative measure between similarly rated devices. 20V rated Schottky diodes are recommended for outputs less than 15V, while 30V rated Schottky diodes are recommended for outputs greater than 15V. The AAT1210 schematic and PCB layout are provided in Figures 2, 6, and 7. The PCB layout includes a small 1 ounce copper power plane on top and bottom layers which is tied to the paddle of the TDFN34-16 package. The top plane is soldered directly to the paddle, and tied to the bottom layer 1400 7 1200 6 VIN = 4.5V 1000 VIN = 3.6V 800 5 Output Current Output Power 4 600 3 400 2 200 Maximum Output Power (W) Maximum Output Current (mA) AAT1210 Boost Converter Maximum Output Capability 1 VIN = 2.7V 0 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Output Voltage (V) Figure 1: Maximum Output Power Vs. Output Voltage for TC(RISE) = +50ºC (assumes TDFN34-16 paddle heatsinking; see Figures 6, 7, and 8). 1210.2007.02.1.2 13 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming D1 Schottky L1 0.47µH 9V at 300mA 5V at 600mA VIN: 2.7V to 5.5V U1 1 2 3 4 5 6 7 8 R1 36.5k C2 4.7µF R2 10V 549 R3 4.99k R4 16 LIN VP 15 LIN VP 14 FB1 EN/SET 13 FB2 SEL 12 GND VIN 11 PGND N/C 10 PGND SW 9 PGND SW AAT1210_TDFN34-16 10K JP1 1 2 3 Enable JP2 C1 4.7uF 1 2 3 Select U1 AAT1210 TDFN34-16 C1 6.3V 0603 4.7µF C2 10V 0805 10µF D1 30V 0.5A MBR0530T1 SOD-123 L1 0.47µH SD10-R47-R R1 36.5k 0603 R2 549 0603 R3 4.99k 0603 R4 10k 0603 Figure 2: AAT1210 Demo Board Schematic. The switching period is divided between ON and OFF time intervals. 1 = TON + TOFF FS During the ON time, the N-channel power MOSFET is conducting and storing energy in the boost inductor. During the OFF time, the N-channel power MOSFET is not conducting. Stored energy is transferred from the input supply and boost inductor to the output load through the output diode. Duty cycle is defined as the ON time divided by the total switching interval. TON D= TON + TOFF = TON ⋅ FS 14 The maximum duty cycle can be estimated from the relationship for a continuous mode boost converter. Maximum duty cycle (DMAX) is the duty cycle at minimum input voltage (VIN(MIN)). DMAX = VOUT - VIN(MIN) VOUT The average diode current during the OFF time can be estimated. IAVG(OFF) = IOUT 1 - DMAX The following curves show the VF characteristics for different Schottky diodes (100°C case). The VF of the Schottky diode can be estimated from the average current during the off time. 1210.2007.02.1.2 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming ode. PCB heatsinking the anode may degrade EMI performance. Forward Current (mA) 10000 B340LA MBR0530 1000 The reverse leakage current of the rectifier must be considered to maintain low quiescent (input) current and high efficiency under light load. The rectifier reverse current increases dramatically at high temperatures. ZHCS350 100 BAT42W Additional considerations may apply to satisfy short circuit conditions. A short circuit across the output terminals results in high currents through the inductor and output diode. The output diode must be sized to prevent damage and possible failure of the diode under short circuit conditions. The inductor may saturate without incurring damage. 10 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 Forward Voltage (V) Figure 3: Forward Voltage vs. Forward Current for Various Schottky Diodes. The average diode current is equal to the output current. When current limit of (3A minimum) is reached, switching of the low side N-channel MOSFET is disabled. Although switching is disabled, DC current continues to build to a level determined by the DC resistance in the path of current flow. For portable applications, the source resistance (RSOURCE) of the Li-ion battery pack is between 100-300mΩ and should also be considered. IAVG(TOT) = IOUT The average output current multiplied by the forward diode voltage determines the loss of the output diode. PLOSS_DIODE = IAVG · VF ISHT-CKT(MAX) = = IOUT · VF The AAT1210 controller will generate an over-temperature (OT) event under extended short circuit conditions. OT disables the high side P-channel MOSFET, which terminates current flow in the output diode. Current flow continues when OT hysteresis (cool-down) is met. This continues until the short circuit condition is removed. In portable applications, the battery pack over-current protection may be enabled prior to an OT event. Diode junction temperature can be estimated. TJ = TAMB + ΘJA · PLOSS_DIODE The junction temperature should be maintained below 110ºC, but may vary depending on application and/or system guidelines. The diode θJA can be minimized with additional PCB area on the cath- Manufacturer Diodes, Inc. ON Semi Zetex Central Semi (VIN(MAX) - VF) (RSOURCE + RDC + RDS(ON)IN) Part Number Rated Forward Current (A) Non-Repetitive Peak Surge Current (A) Rated Voltage (V) Thermal Resistance θJA, °C/W) (θ Case BAT42W MBR0530T ZHCS350 CMDSH2-3 0.2 0.5 0.35 0.2 4.0 5.5 4.2 1.0 30 30 40 30 500 206 330 500 SOD-123 SOD-123 SOD-523 SOD-323 Table 1: Typical Surface Mount Schottky Rectifiers for Various Output Levels. 1210.2007.02.1.2 15 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Selecting the Boost Inductor The AAT1210 controller utilizes hysteretic control and the switching frequency varies with output load and input voltage. The value of the inductor determines the maximum switching frequency of the boost converter. Increased output inductance decreases the switching frequency, resulting in higher peak currents and increased output voltage ripple. The required inductance increases with increasing output voltage. The inductor is sized from 0.47µH to 2.2µH for output voltages from 5V to 18V. This selection maintains high frequency switching (up to 2MHz), low output ripple and minimum solution size. A summary of recommended inductors and capacitors for 5V to 18V fixed outputs is provided in Table 2. The physical size of the inductor may be reduced when operating at greater than 2.7V input voltage and/or less than maximum rated output power is desired (see Figure 1 for maximum output power estimate). Figure 4 provides the peak inductor current (IPEAK) versus output power for different input voltage levels. The curves are valid for all output voltages and assume the corresponding inductance value provided in Figure 4. The inductor is selected to maintain IPEAK current less than the specified saturation current (ISAT). AAT1210 Peak Inductor Current vs. Output Power Peak Inductor Current (mA) The diode non-repetitive peak surge current (IFSM) rating should be greater than ISHT_CKT(MAX) to ensure diode reliability under short circuit conditions. Typically, IFSM current is specified for conduction periods from 8-10ms. If short circuit survivability is required, it is recommended to verify ISHT_CKT(MAX) under actual operating conditions across the expected operating temperature range. 3500 VIN = 3.6V VIN = 2.7V 3000 2500 2000 VIN = 4.5V 1500 1000 500 0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 Output Power (W) Figure 4: Peak Inductor Current (IPEAK) vs. Output Power. The RMS current flowing through the boost inductor is equal to the DC plus AC ripple components. Under worst-case RMS conditions, the current waveform is critically continuous. The resulting RMS calculation yields worst-case inductor loss. The RMS value should be compared against the manufacturer's temperature rise, or thermal derating, guidelines. IRMS = IPEAK 3 In most cases, the inductor's specified IRMS current will be greater than the IRMS current required by the boost inductor. For a given inductor type, smaller inductor size leads to an increase in DCR winding resistance and, in most cases, increased thermal impedance. Winding resistance degrades boost converter efficiency and increases the inductor operating temperature. PLOSS_INDUCTOR = IRMS2 · DCR VOUT C1 (Input Capacitor) C2 (Output Capacitor) L1 (Boost Inductor) 5.0 9.0 12.0 15.0 18.0 4.7µF 4.7µF 4.7µF 4.7µF 4.7µF 10µF/6.3V, 10V 10µF/10V 10µF/16V 10µF/16V 4.7µF/25V 0.47µH 0.47µH 1.0/1.2µH 1.0/1.2µH 2.2µH Table 2: Output Inductor and Capacitor Values Vs. Output Voltage 16 1210.2007.02.1.2 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming To ensure high reliability, the inductor temperature should not exceed 100ºC. Manufacturer's recommendations should be consulted. In some cases, PCB heatsinking applied to the AAT1210 LIN node (nonswitching) can improve the inductor's thermal capability. PCB heatsinking may degrade EMI performance when applied to the SW node (switching) of the AAT1210. Shielded inductors provide decreased EMI and may be required in noise sensitive applications. Unshielded chip inductors provide significant space savings at a reduced cost compared to shielded (wound and gapped) inductors. Chip-type inductors have increased winding resistance when compared to shielded, wound varieties. Manufacturer Sumida www.sumida.com Murata www.murata.com Cooper www.cooperet.com Selecting DC/DC Boost Capacitors Recommended input and output capacitors for output voltages from 5V to 18V are provided in Table 4. The high output ripple inherent in the boost converter necessitates low impedance output filtering. Multilayer ceramic (MLC) capacitors provide small size and high capacitance, low parasitic equivalent series resistance (ESR) and equivalent series inductance (ESL), and are well suited for use with the AAT1210 boost regulator. MLC capacitors of type X7R or X5R are recommended to ensure good capacitance stability over the full operating temperature range. Max Max IRMS DC ISAT Inductance Current Current DCR Ω) (µH) (A) (A) (mΩ Part Number CDRH5D16-1R4 CDRH5D16-1R4 CDRH3D11/HP-1R5 CDRH3D11/HP-2R7 LQH55DNR47M03 LQH55DN1R0M03 LQH55DN1R5M03 LQH55DN2R2M03 SD3814-R47 SD3814-1R2 SD3814-2R2 SD10-R47-R SD10-1R0-R SD10-2R2-R SD18-2R2-R 1.4 2.2 1.5 2.7 0.47 1.0 1.5 2.2 0.47 1.2 2.2 0.47 1 2.2 2.2 4.7 3.0 2.0 1.55 4.8 4.0 3.7 3.2 4.44 2.67 1.9 3.54 2.25 1.65 2.16 4.7 2.85 1.45 1.3 2.81 1.85 1.43 2.59 1.93 1.35 2.55 14.6 35.9 80 100 13 19 22 29 20 46 77 24.9 44.8 91.2 39.8 Size LxWxH (mm) Type 5.8x5.8x1.8 5.8x5.8x1.8 4.0x4.0x1.2 4.0x4.0x1.2 5.7x5.0x4.7 5.7x5.0x4.7 5.7x5.0x4.7 5.7x5.0x4.7 4.0x4.0x1.4 4.0x4.0x1.4 4.0x4.0x1.4 5.2x5.2x1.0 5.2x5.2x1.0 5.2x5.2x1.0 5.2x5.2x1.8 Shielded Shielded Shielded Shielded Non-Shielded Non-Shielded Non-Shielded Non-Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Table 3: Recommended Inductors. Manufacturer Part Number Murata www.murata.com GRM188R60J475KEAD GRM21BR61A475KA73L GRM21BR61E475KA12L GRM188R60J106ME47D GRM21BR61A106KE19L GRM219R61A106KE44D GRM21BR61C106KE15L Value (µF) Voltage Rating (V) Temp. Co. Case Size 4.7 4.7 4.7 10 10 10 10 6.3 10 25 6.3 10 10 16 X5R X5R X5R X5R X5R X5R X5R 0603 0805 0805 0603 0805 0805 (H = 0.85mm) 0805 Table 4: Recommended MLC Capacitors. 1210.2007.02.1.2 17 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming The output capacitor is sized to maintain the output load without significant voltage droop (ΔVOUT) during the power switch ON interval, when the output diode is not conducting. A ceramic output capacitor from 4.7µF to 10µF is recommended. Output capacitors should be rated from 10V to 25V, depending on the maximum desired output voltage. Ceramic capacitors sized as small as 0603 are available which meet these requirements. Minimum 6.3V rated ceramic capacitors are required at the input. Ceramic capacitors sized as small as 0603 are available which meet these requirements. Output capacitors should be rated from 6.3V to 25V, depending on the maximum desired output voltage. MLC capacitors exhibit significant capacitance reduction with applied voltage. Output ripple measurements should confirm that output voltage droop and converter stability is acceptable. Voltage derating can minimize this factor, but results may vary with package size and among specific manufacturers. Output capacitor size can be estimated at a switching frequency (FSW) of 500kHz (worst-case). I · DMAX COUT = OUT FS · ΔVOUT The boost converter input current flows during both ON and OFF switching intervals. The input ripple current is less than the output ripple and, as a result, less input capacitance is required. A ceramic output capacitor from 4.7µF to 10µF is recommended. The voltage rating of the capacitor must be greater than, or equal to, the maximum operating output voltage. X5R ceramic capacitors are available in 6.3V, 10V, 16V and 25V rating. Ceramic capacitors sized as small as 0603 are available which meet these requirements. Minimum 6.3V rated ceramic capacitors are required at the input. Ceramic capacitors sized as small as 0603 are available which meet these requirements. 18 Setting the Output Voltage The minimum output voltage must be greater than the specified maximum input voltage plus 0.5V margin to maintain proper operation of the AAT1210 boost converter. The output voltage may be programmed through a resistor divider network located from the output to FB1 and FB2 pins to ground. Pulling the SEL pin high activates the FB1 pin which maintains a 1.2V reference voltage, while the FB2 reference is disabled. Pulling the SEL pin low activates the FB2 pin which maintains a 0.6V reference, while the FB1 reference is disabled. The AAT1210 output voltage can be programmed by one of three methods. First, the output voltage can be static by pulling the SEL logic pin either high or low. Second, the output voltage can be dynamically adjusted between two pre-set levels within a 2X operating range by toggling the SEL logic pin. Third, the output can be dynamically adjusted to any of 16 preset levels within a 2X operating range using the integrated S2Cwire single wire interface via the EN/SET pin. See Table 5 for static and dynamic output voltage settings. Table 5 provides details of resistor values for common output voltages from 5V to 18V for SEL = High and SEL = Low options. SEL = High corresponds to VOUT(1) and SEL = Low corresponds to VOUT(2). Option 1: Static Output Voltage Most DC/DC boost converter applications require a static (fixed) output voltage. If a static voltage is desired, the FB1 pin should be connected directly to FB2 and a resistor between FB1 and FB2 pins is not required. A static output voltage can be configured by pulling the SEL either high or low. SEL pin high activates the FB1 reference pin to 1.2V (nominal). Alternatively, the SEL pin is pulled low to activate the FB2 reference at 0.6V (nominal). Table 5 provides details of resistor values for common output voltages from 5V to 18V for SEL = High and SEL = Low options. 1210.2007.02.1.2 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Option 2: Dynamic Voltage Control Using SEL Pin The output may be dynamically adjusted between two output voltages by toggling the SEL logic pin. Output voltages VOUT(1) and VOUT(2) correspond to the two output references, FB1 and FB2. Pulling the SEL logic pin high activates VOUT(1), while pulling the SEL logic pin low activates VOUT(2). In addition, the ratio of output voltages VOUT(2)/VOUT(1) is always less than 2.0, corresponding to a 2X (maximum) programmable range. Option 3: Dynamic Voltage Control Using S2Cwire Interface The output can be dynamically adjusted by the host controller to any of 16 pre-set output voltage levels using the integrated S2Cwire interface. The EN/SET pin serves as the S2Cwire interface input. The SEL pin must be pulled low when using the S2Cwire interface. S2Cwire Serial Interface AnalogicTech's S2Cwire serial interface is a proprietary high-speed single-wire interface. The S2Cwire interface records rising edges of the EN/SET input and decodes into 16 different states. Each state corresponds to a voltage setting on the FB2 pin, as shown in Table 6. S2Cwire Output Voltage Programming The AAT1210 is programmed through the S2Cwire interface according to Table 6. The rising clock edges received through the EN/SET pin determine the feedback reference and output voltage setpoint. Upon power-up with the SEL pin low and prior to S2Cwire programming, the default feedback reference voltage is set to 0.6V. 1210.2007.02.1.2 Ω VOUT(1) VOUT(2) R3 = 4.99kΩ Ω) R2 (kΩ Ω) (SEL = High) (SEL = Low) R1 (kΩ 5.0V 6.0V 7.0V 8.0V 9.0V 10.0V 12.0V 15.0V 16.0V 18.0V 9.0V 10.0V 12.0V 15.0V 15.0V 16.0V 18.0V 15.0V 16.0V 18.0V 18.0V 5.0V 6.0V 7.0V 8.0V 9.0V 10.0V 12.0V 15.0V 16.0V 18.0V 5.0V 9.0V 10.0V 10.0V 12.0V 10.0V 10.0V 12.0V 12.0V 12.0V 15.0V 15.8 20.0 24.3 28.0 32.4 36.5 44.2 57.6 61.9 69.8 36.5 45.3 53.6 61.9 69.8 78.7 95.3 121 127 143 36.5 66.5 75 76.8 90.9 76.8 78.7 90.9 93.1 93.1 115 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.549 4.02 3.32 1.65 3.01 1.24 0.562 3.01 2.49 1.65 3.32 Table 5: SEL Pin Voltage Control Resistor Values (1% resistor tolerance). 19 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming EN/SET Rising Edges FB2 Reference Voltage (V) EN/SET Rising Edges FB2 Reference Voltage (V) 1 2 3 4 5 6 7 8 0.60 (Default) 0.64 0.68 0.72 0.76 0.80 0.84 0.88 9 10 11 12 13 14 15 16 0.92 0.96 1.00 1.04 1.08 1.12 1.16 1.20 attempt should be made to optimize the layout in order to minimize parasitic PCB effects (stray resistance, capacitance, inductance) and EMI coupling from the high frequency SW node. A suggested PCB layout for the AAT1210 boost converter is shown in Figures 6, 7, and 8. The following PCB layout guidelines should be considered: 1. Minimize the distance from Capacitor C1 and C2 negative terminal to the PGND pins. This is especially true with output capacitor C2, which conducts high ripple current from the output diode back to the PGND pins. 2. Place the feedback resistors close to the output terminals. Route the output pin directly to resistor R1 to maintain good output regulation. R3 should be routed close to the output GND pin, but should not share a significant return path with output capacitor C2. 3. Minimize the distance between L1 to D1 and switching pin SW; minimize the size of the PCB area connected to the SW pin. 4. Maintain a ground plane and connect to the IC PGND pin(s) as well as the GND terminals of C1 and C2. 5. Consider additional PCB area on D1 cathode to maximize heatsinking capability. This may be necessary when using a diode with a high VF and/or thermal resistance. 6. To maximize thermal capacity, connect the exposed paddle to the top and bottom power planes using plated through vias. Top and bottom planes should not extend far beyond the TDFN34-16 package boundary to minimize stray EMI. Table 6: S2Cwire Voltage Control Settings (SEL = Low). S2Cwire Serial Interface Timing The S2Cwire serial interface has flexible timing. Data can be clocked-in at speeds up to 1MHz. After data has been submitted, EN/SET is held high to latch the data for a period TLAT. The output is subsequently changed to the predetermined voltage. When EN/SET is set low for a time greater than TOFF, the AAT1210 is disabled. When disabled, the register is reset to the default value, which sets the FB2 pin to 0.6V if EN is subsequently pulled high. PCB Layout Boost converter performance can be adversely affected by poor layout. Possible impact includes high input and output voltage ripple, poor EMI performance, and reduced operating efficiency. Every THI TLO TOFF T LAT EN/SET 1 Data Reg 2 n-1 n ≤ 16 0 n-1 0 Figure 5: S2Cwire Timing Diagram. 20 1210.2007.02.1.2 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Figure 6: AAT1210 Evaluation Board Top Side Layout. Figure 7: AAT1210 Evaluation Board Bottom Side Layout. Figure 8: Exploded View of AAT1210 Evaluation Board Top Side Layout Detailing Plated Through Vias. 1210.2007.02.1.2 21 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Ordering Information Package Marking1 Part Number (Tape and Reel)2 TDFN34-16 VDXYY AAT1210IRN-0.6-T1 All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means semiconductor products that are in compliance with current RoHS standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more information, please visit our website at http://www.analogictech.com/pbfree. Package Information3 TDFN34-16 3.000 ± 0.050 1.600 ± 0.050 Detail "A" 3.300 ± 0.050 4.000 ± 0.050 Index Area 0.350 ± 0.100 Top View 0.230 ± 0.050 Bottom View C0.3 (4x) 0.050 ± 0.050 0.450 ± 0.050 0.850 MAX Pin 1 Indicator (optional) 0.229 ± 0.051 Side View Detail "A" All dimensions in millimeters. 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. 3. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection. 22 1210.2007.02.1.2 AAT1210 High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming © Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicTech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech’s standard warranty. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders. Advanced Analogic Technologies, Inc. 830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737- 4600 Fax (408) 737- 4611 1210.2007.02.1.2 23