NX7102 3A High Voltage Synchronous Buck Converter PRODUCTION DATA SHEET DESCRIPTION KEY FEATURES NX7102 is a 340kHz fixed The controller is equipped with  3A Synchronous Step-down W frequency, current mode, PWM output over-voltage protection which Regulator W synchronous buck (step-down) DC- protects the IC under an open load  Operational Input Supply W DC converter, capable of driving a 3A condition. Additional safety features Voltage Range: 4. 5V-18V M. load with high efficiency, excellent include under voltage lock-out  Integrated Upper NMOS and ic line and load regulation. The device (UVLO), programmable soft-start and Lower NMOS r o integrates N-channel power MOSFET over-temperature protection (OTP) to  340kHz Switching Frequency s e switches with low on-resistance. protect the circuit.  Input UVLO m Current mode control provides fast This IC is available in SOIC-8 with  Enable i . transient response and cycle-by-cycle exposed pad package.  Programmable External Soft- C O current limit. Start M  Cycle-By-Cycle Over-Current Protection  Over Voltage Protection  Frequency Fold Back Under Short Condition APPLICATIONS  Set-Top Box  LCD TV’s  Notebook/Netbook  PoE Powered Devices PRODUCT HIGHLIGHT 12V VIN IN(2) BST(1) CIN C5 2x10uF(25V,X5R) NX7102 10nF L1 C4 0.1u 10uH 3.3V SS(8) SW(3) OUT R1 R4 100k 26.1k COUT EN(7) 2*22uF(10V,X5R) FB(5) GND(4) PAD COMP(6) R2 10k R3 10k C3 5.6nF Figure 1 – 12V Input, 3.3V Output with Ceramic Cap N X PACKAGE ORDER INFO 7 Plastic SOIC 8 Pin DE 1 TA (C) With Exposed Pad 0 RoHS Compliant / Pb-free 2 -40 to 85 NX7102IDE Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. NX7102IDE-TR) Copyright  2010 Microsemi Page 1 Rev.1.6, 2015-02-20 Analog Mixed Signal Group One Enterprise, Aliso Viejo, CA, 949-380-6100, Fax: 949-215-4996

NX7102 3A High Voltage Synchronous Buck Converter PRODUCTION DATA SHEET ABSOLUTE MAXIMUM RATINGS PACKAGE PIN OUT Supply Input Voltage (VIN) ............................................................................ -0.3V to 20V W Switch Voltage (SW) ............................................................................. -1V to (VIN + 1V) BST 1 8 SS W EN ................................................................................................... -0.3V to (VIN + 0.3V) X7M W BCMSOaTxMi m.P..,u. .Fm..B. .O.,. .Sp..Se..r .a ....t..i..n....g.... ..J..u....n....c....t..i..o....n.... ..T......e..m......p....e....r..a....t..u....r....e.. ..................................................................................................................... ..-..0.......3....V...... ..t..o.... ..( .V-..0.S...3W.V.. 1 +t5o 06 6VVC) VSIWN 32 X X X 1 0 2 I D S C 67 CENOMP Micr. Storage Temperature Range .........................................................................-65C to 150C GND 4 E 5 FB os Package Peak Temp. for Solder Reflow (40 seconds maximum exposure) ................ 260°C e m DE PACKAGE Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to (Top View) i . C Ground. Currents are positive into, negative out of specified terminal. DE PART MARKING O “xxxx” Denote Date Code and Lot Identification M RoHS / Pb-free 100% Matte Tin Pin Finish THERMAL DATA DE Plastic SOIC 8-Pin With Exposed Pad THERMAL RESISTANCE-JUNCTION TO AMBIENT, JA 60C/W Junction Temperature Calculation: T = T + (P x  ). J A D JA The  numbers are guidelines for the thermal performance of the device/pc-board system. All of the JA above assume no ambient airflow. FUNCTIONAL PIN DESCRIPTION Pin Name Description Bootstrap pin. A minimum 10nF bootstrap capacitor is connected between the BS pin and SW pin. 1 BST The voltage across the bootstrap capacitor drives the internal high side NMOS. Supply input pin. A capacitor should be connected between the VIN pin and GND pin to keep the 2 VIN input voltage constant. 3 SW Power switch output pin. This pin is connected to the inductor and bootstrap capacitor. 4 GND Ground. Feedback pin. This pin is connected to an external resistor divider to program the system output voltage. When the FB pin voltage exceeds 20% of the nominal regulation value of 0.925V, the 5 FB over voltage protection is triggered. When the FB pin voltage is below 0.3V, the oscillator frequency is lowered to realize short circuit protection. Compensation pin. This pin is the output of the transconductance error amplifier and the input to 6 COMP the current comparator. It is used to compensate the control loop. Connect a series RC network from this pin to GND. In some cases, an additional capacitor from this pin to GND pin is required. Control input pin. Forcing this pin above 2.7V enables the IC. Forcing this pin below 1.1V shuts 7 EN down the IC. When the IC is in shutdown mode, all functions are disabled to decrease the supply N current below 1μA. X Soft-start control input pin. SS controls the soft start period. Connect a capacitor from SS to GND 8 SS to set the soft-start period. A 0.1μF capacitor sets the soft-start period to 9ms. To disable the soft- 7 start feature, leave SS unconnected. 1 0 2 Copyright  2010 Microsemi Page 2 Rev.1.6, 2015-02-20 Analog Mixed Signal Group One Enterprise, Aliso Viejo, CA, 949-380-6100, Fax: 949-215-4996

NX7102 3A High Voltage Synchronous Buck Converter PRODUCTION DATA SHEET RECOMMENDED OPERATING CONDITIONS W NX7102 Parameter Symbol Units W Min Typ Max W Input Operating Voltage VIN 4. 5 18 V M. Maximum Output Current I 3 A OUTMAX ic Operating Ambient Temperature TA -40 85 °C r o s e ELECTRICAL CHARACTERISTICS m Unless otherwise specified, the following specifications apply for VIN = VEN =12V, VOUT = 5V, TA = 25C. i .C NX7102 O Parameter Symbol Test Conditions Units Min Typ Max M  Operating Current Quiescent Current I V = 1V 1.25 1.4 mA Q FB Shutdown Current I V = 0V .02 1 µA SHDN EN  UVLO V UVLO Threshold V V Rising 3.65 4.00 4.25 V IN UVLO IN Hysteresis V 0.2 V HYS  Feedback Feedback Voltage V T = -40°C to 85°C 0.907 0.925 0.943 V FB A Feedback Bias Current I V = 1V -0.1 0.1 µA FB FB  Oscillator Internal Oscillator Frequency F 280 340 400 kHz OSC1 Short Circuit Oscillator F 100 kHz Frequency OSC2 Maximum Duty Cycle D V = 0.8V 90 % MAX FB Minimum Duty Cycle D V = 1V 0 % MIN FB  Error Amplifier Error Amplifier G 800 µA/V Transconductance EA Voltage Gain(1) A 400 V/V EA  Current Sensing Gain Current Sensing Gain G 5.2 A/V CS  Soft-Start Soft-start Current 6 µA Soft-start Time T C = 0.1µF 15 ms SS SS  Output Stage High-side Switch On Resistance R 90 120 150 mΩ DSONH Low-side Switch On Resistance R 70 100 130 mΩ DSONL High-side Switch Leakage I VIN = 18V, V = 0V, V = 0V 0.1 10 µA Current LEAKH EN SW High-side Switch Current Limit I 4.3 5.5 6.7 A N LIMH Low-side Switch Current Limit I 0.85 1.45 2.05 A X LIML  EN 7 1 EN shutdown Threshold V 1.1 1.5 2 V ENH 0 EN shutdown Threshold 2 V 350 mV Hysteresis ENL Copyright  2010 Microsemi Page 3 Rev.1.6, 2015-02-20 Analog Mixed Signal Group One Enterprise, Aliso Viejo, CA, 949-380-6100, Fax: 949-215-4996

NX7102 3A High Voltage Synchronous Buck Converter PRODUCTION DATA SHEET ELECTRICAL CHARACTERISTICS (CONT) Unless otherwise specified, the following specifications apply for V = V =12V, V = 5V, T = 25C. IN EN OUT A W NX7102 Parameter Symbol Test Conditions Units W Min Typ Max W EN Lockout Threshold 2.2 2.5 2.7 M. EN Lockout Hysteresis 210 mV  Protection ic r Over Voltage Protection o V 1.1 V s Threshold FBOV e m FB Short Circuit Protection 0.23 0.3 0.41 V Thermal Shutdown Threshold TOTSD 160 °C i .C Thermal Shutdown Hysteresis T 30 °C HYS O Note s: M 1) Guaranteed by design, not tested. SIMPLIFIED BLOCK DIAGRAM 1.5V SD Bias Regualtor EN 0.925V Osc slope 340k/90k compensation VIN Current VCC Thermal Sensing SD UVLO shutdown BST UVLO PWM LOGIC D SS Soft Start river SW FB COMP 2.5V 1.3V EN Low Side Current Limit GND N 0.3V FB UVLO X 7 1 0 2 Figure 2 – Simplified Block Diagram Copyright  2010 Microsemi Page 4 Rev.1.6, 2015-02-20 Analog Mixed Signal Group One Enterprise, Aliso Viejo, CA, 949-380-6100, Fax: 949-215-4996

NX7102 3A High Voltage Synchronous Buck Converter PRODUCTION DATA SHEET APPLICATION CIRCUIT W W W . M ic r o s e VIN IN(2) BST(1) m C2xIN(10uF,25V) NX7102 C105nF L1 i .C C4 0.1uSS(8) SW(3) 22uH OUT OM R1 R4 100k 42.2k COUT EN(7) 1000uF,170mohm FB(5) GND(4) PAD COMP(6) R2 9.53k C6 2200pF Figure 3 – 12V Input, 5V Output with Electrolytic Cap N X 7 1 0 2 Copyright  2010 Microsemi Page 5 Rev.1.6, 2015-02-20 Analog Mixed Signal Group One Enterprise, Aliso Viejo, CA, 949-380-6100, Fax: 949-215-4996

NX7102 3A High Voltage Synchronous Buck Converter PRODUCTION DATA SHEET W W W . VIN IN(2) BST(1) M C2*I1N0uF(25V,X5R) NX7102 C105nF L1 ic r C4 0.1u 10uH o SS(8) SW(3) OUT s e R1 m R4 100k EN(7) FB(5) R422. 2k C2*O2U2uTF(10V,X5R) i .C GND(4) PAD COMP(6) 9.53k O M R3 10k C3 5.6nF Figure 4 – 12V Input, 5V Output with Ceramic Cap TYPICAL WAVEFORMS @ 25°C (REFER TO FIGURE 3) N X 7 1 0 Figure 5. DC Operation at 3A Figure 6. Transient Response 2 Copyright  2010 Microsemi Page 6 Rev.1.6, 2015-02-20 Analog Mixed Signal Group One Enterprise, Aliso Viejo, CA, 949-380-6100, Fax: 949-215-4996

NX7102 3A High Voltage Synchronous Buck Converter PRODUCTION DATA SHEET W W W . M ic r o s e m i . C O M Figure 7. Start up with no load Figure 8. Input power recycling TYPICAL WAVEFORMS @ 25°C (REFER TO FIGURE 3) N X 7 1 0 2 Figure 9. Start into 2A resistive load Figure 10. Output short operation Copyright  2010 Microsemi Page 7 Rev.1.6, 2015-02-20 Analog Mixed Signal Group One Enterprise, Aliso Viejo, CA, 949-380-6100, Fax: 949-215-4996

NX7102 3A High Voltage Synchronous Buck Converter PRODUCTION DATA SHEET W 100% 100% W W 90% 90% . M 80% 80% ic r o 70% 70% s e 60% 60% m y cienc 50% ncy 50% i .C Effi 40% Efficie40% OM 30% 30% 20% 20% 10% VOUT=1V VOUT=1.8V 10% VOUT = 1V VOUT = 1.8V VOUT=2.5V VOUT=3.3V VOUT = 2.5V VOUT = 3.3V 0% 0% 0 500 1000 1500 2000 2500 3000 0 500 1000 1500 2000 2500 3000 Load Current (mA) Load Current (mA) Figure 11. NX7102 Efficiency VS Load ( VIN=5V) Figure 12. NX7102 Efficiency VS Load ( VIN=12V) N X 7 1 0 2 Copyright  2010 Microsemi Page 8 Rev.1.6, 2015-02-20 Analog Mixed Signal Group One Enterprise, Aliso Viejo, CA, 949-380-6100, Fax: 949-215-4996

NX7102 3A High Voltage Synchronous Buck Converter PRODUCTION DATA SHEET THEORY OF OPERATION W DETAIL DESCRIPTION When FB pin voltage exceeds 1.1V, the over voltage W protection is triggered. The high side MOSFET is turned off. The NX7102 is a current-mode, PWM synchronous step- W Once the OVP condition is gone, the chip will resume the down DC-DC converter with 340kHz fixed working M. operation following soft-start. frequency. It can convert input voltages from 4. 5V to 18V ic down to an output voltage as low as 0.925V, and supply up The soft-start time is programmable through the SS pin in ro to 3A load current. order to have desired soft-start time s e The NX7102 has two internal N-MOSFETs to step down the When the input voltage falls below the UVLO threshold, the m voltage. The inductor current is determined by sensing the Lower Side MOSFET turns to discharge the output i internal high-side MOSFET current. The output of current capacitance. .C O sense amplifier is summed with the slope compensation M signal to avoid sub-harmonic oscillation at duty cycles greater than 50%. The combined signal is then compared with the error amplifier output to generate the PWM signal. Current mode control provides no only fast control loop response but also cycle-by-cycle current limit protection. When load current reaches its maximum output level when the inductor peak current triggers high-side NMOFET current limit. If FB pin voltage drops below 0.3V, the working frequency will be fold back to typically 100kHz to protect chip from run-away. N X 7 1 0 2 Copyright  2010 Microsemi Page 9 Rev.1.6, 2015-02-20 Analog Mixed Signal Group One Enterprise, Aliso Viejo, CA, 949-380-6100, Fax: 949-215-4996

NX7102 3A High Voltage Synchronous Buck Converter PRODUCTION DATA SHEET APPLICATION INFORMATION W Where ESR is the output capacitor’s equivalent series SYMBOL USED IN APPLICATION INFORMATION: W resistance, C is the value of output capacitor. OUT W VIN - Input voltage Typically when large value capacitors are selected such as M. V - Output voltage Aluminum Electrolytic, POSCAP and OSCON types are used, OUT ic I - Output current the amount of the output voltage ripple is dominated by the first r OUT o V - Output voltage ripple term in equation(2) and the second term can be neglected. s RIPPLE e F - Working frequency If ceramic capacitors are chosen as output capacitors, both m SIRIPPLE - Inductor current ripple toevremras lli nr ipepqluea. tUiosnu a(l2l)y nweheedn ttoh ibs et yepvea loufa tceadp atcoi todre tiesr mseilneec ttehde, i .C DESIGN EXAMPLE the amount of capacitance per single unit is not sufficient to OM meet the transient specification, which results in parallel The following is typical application for NX7102, the configuration of multiple capacitors. schematic is figure 1. In this design two 22μF 6.3V X5R ceramic capacitors are V = 12V IN chosen as output capacitors. V = 3.3V OUT INPUT CAPACITOR SELECTION I = 3A OUT Input capacitors are usually a mix of high frequency ceramic OUTPUT INDUCTOR SELECTION capacitors and bulk capacitors. Ceramic capacitors bypass the The selection of inductor value is based on inductor ripple high frequency noise, and bulk capacitors supply current to the current, power rating, working frequency and efficiency. A MOSFETs. Usually 1uF ceramic capacitor is chosen to larger inductor value normally means smaller ripple current. decouple the high frequency noise. The bulk input capacitors However if the inductance is chosen too large, it results in are determined by voltage rating and RMS current rating. The slow response and lower efficiency. Usually the ripple RMS current in the input capacitors can be calculated as: current ranges from 20% to 40% of the output current. This I I  D 1-D is a design freedom which can be determined by the design RMS OUT engineer according to various application requirements. The V ... (3) D OUT inductor value can be calculated by using the following V IN equations: In this design two 10uF 25V X5R ceramic capacitors are V -V V 1 chosen. L  IN OUT  OUT  OUT I V F RIPPLE IN S OUTPUT VOLTAGE CALCULATION I kI RIPPLE OUTPUT ... (1) O u t p u t v o l t a g e i s s e t b y r e f e r e n c e voltage and external voltage where k is between 0.2 to 0.4. divider. The reference voltage is fixed at 0.925V. The divider In this design, k is set at 0.23 and 10μH inductor value is consists of the ratio of two resistors so that the output voltage chosen. In order to avoid output oscillation at light load, a applied at the FB pin is 0.925V when the output voltage is at the desired value. The following equation and picture show the minimum 8.2μH inductor is required for all NX7102 relationship between and voltage divider. application. OUTPUT CAPACITOR SELECTION Vout NX7102 Output capacitor is basically decided by the amount of the N output voltage ripple allowed during steady state(DC) load R1 X FB condition as well as specification for the load transient. The COMP 7 optimum design may require a couple of iterations to satisfy 1 both conditions. R2 0 The amount of voltage ripple during the DC load condition is Vref 2 determined by equation (2). I V ESRI  RIPPLE ... (2) Figure 13 Voltage Divider RIPPLE RIPPLE 8F C S OUT The pole P3 set by R3 and C6 is given by the equation (10). Copyright  2010 Microsemi Page 10 Rev.1.6, 2015-02-20 Analog Mixed Signal Group One Enterprise, Aliso Viejo, CA, 949-380-6100, Fax: 949-215-4996

NX7102 3A High Voltage Synchronous Buck Converter PRODUCTION DATA SHEET APPLICATION INFORMATION W V =V (1+R1) ... (4) F = 1 ... (10) W OUT REF R P3 2R C W 2 3 6 In this design choose R1 26.1k, choose R2 10k. The compensation values for typical output voltage application M. COMPENSATOR DESIGN are given in the table below. ic r o The NX7102 uses peak current mode control to provide fast V L C R3 C3 C6 s OUT OUT e transient and simple compensation. The DC gain of close 1.8V 8.2μH 22μFx2 4.02kΩ 5.6nF None m loop can be estimated by the equation (5). 2.5V 10μH 22μFx2 5.11kΩ 5.6nF None i . C V 3.3V 10μH 22μFx2 6.49kΩ 5.6nF None Gain=A G R  FB ... (5) O EA CS LOAD V 5V 10μH 22μFx2 10kΩ 5.6nF None M OUT Where A is error amplifier voltage gain 560V/V, G is 470μF AL. EA CS current sensing gain 5.2A/V, R is the load resistor. 2.5V 10μH 30m ESR 40.2kΩ 390pF 220pF LOAD The system itself has one pole P1, one zero Z1 and double 470μF AL. pole P at half of switching frequency F . 5V 10-15μH 30m ESR 150kΩ 220pF 120pF DOUBLE S The system pole P1 is set by output capacitor and output load resistor. The calculation of this pole is given by the equation (6). 1 F  ... (6) P1 2R C L OUT The system zero Z1 is set by output capacitor and ESR of output capacitor. The calculation of this zero is given by the equation (7). 1 F = ... (7) Z1 2R C ESR OUT The crossover frequency is recommended to be set at 1/10th of switching frequency. In order to achieve this desired crossover frequency and make system stable, the resistor R3 and the capacitor C3 is needed in typical applications which use ceramic capacitors as output capacitors. The pole P2 set by output resistance of error amplifier and C3 is given by the equation (8). G F = EA ... (8) P2 2A C EA 3 Where G is error amplifier transconductance 800μA/V. EA The zero Z2 set by R3 and C3 is given by the equation (9). 1 N F = ... (9) Z2 2R C X 3 3 When Aluminum Electrolytic capacitors are chosen as output 7 1 capacitors, the ESR zero is much lower and extra capacitor 0 C6 from COMP pin to ground is needed to stabilize the 2 system. Copyright  2010 Microsemi Page 11 Rev.1.6, 2015-02-20 Analog Mixed Signal Group One Enterprise, Aliso Viejo, CA, 949-380-6100, Fax: 949-215-4996

NX7102 3A High Voltage Synchronous Buck Converter PRODUCTION DATA SHEET PACKAGE DIMENSIONS W W DE Plastic SOIC 8 Pin With Exposed Pad W . M ic r o s e m i . C O M N X 7 1 0 2 Copyright  2010 Microsemi Page 12 Rev.1.6, 2015-02-20 Analog Mixed Signal Group One Enterprise, Aliso Viejo, CA, 949-380-6100, Fax: 949-215-4996

NX7102 3A High Voltage Synchronous Buck Converter PRODUCTION DATA SHEET NOTES W W W . M ic r o s e m i . C O M N X 7 PRODUCTION DATA – Information contained in this document is proprietary to 1 Microsemi and is current as of publication date. This document may not be modified in 0 any way without the express written consent of Microsemi. Product processing does not necessarily include testing of all parameters. Microsemi reserves the right to change the 2 configuration and performance of the product and to discontinue product at any time. Copyright  2010 Microsemi Page 13 Rev.1.6, 2015-02-20 Analog Mixed Signal Group One Enterprise, Aliso Viejo, CA, 949-380-6100, Fax: 949-215-4996