nx2139a Microsemi Corporation, nx2139a Datasheet
nx2139a
Related parts for nx2139a
nx2139a Summary of contents
Page 1
... SINGLE CHANNEL MOBILE PWM AND LDO CONTROLLER DESCRIPTION The NX2139A controller compact Buck control- ler IC with 16 lead MLPQ package designed for step down converter in portable applications. It can be selected to operate in synchronous mode or non-synchronous mode to improve the efficiency at light load.Constant on time control provides fast response, good line regulation and nearly constant frequency un- der wide voltage input range ...
Page 2
... Shut down current Rev. 2.3 03/19/ 150 150 HDRV OCSET 10 PVCC SYM Test Condition V IN ENLDO=GND, ENSW=GND V CC VFB=0.85V, ENLDO=GND, ENSW=5V ENLDO=GND, ENSW=GND NX2139A o =25 C, unless otherwise A Min TYP MAX Units V 4 4.5 5 ...
Page 3
... I=200mA sink 10% to 90% 90% to 10% Ldrv going Low to Hdrv going H) High, 10% to 10% (Ldrv) I=200mA source R (Ldrv) I=200mA sink 10% to 90% 90% to 10% SW going Low to Ldrv going L) High, 10% to 10% NX2139A Min TYP MAX Units 3.9 4.1 4.5 V 3.7 3.9 4 312 390 468 ns 380 590 ...
Page 4
... NOTE1: This parameter is guaranteed by design but not tested in production(GBNT). Rev. 2.3 03/19/09 SYM Test Condition Leave it open or use limits in spec ENSW/MODE=VCC ENSW/MODE=GND PWM OFF, LDOEN=HI, IOUT=0mA NOTE1 LDOFB=0.72V LDOFB=0.78V NOTE1 NOTE1 Forward current=50mA NX2139A Min TYP MAX Units 80% VCC+0 VCC .3V V 60% 80% VCC VCC V 60% 2 ...
Page 5
... GND for shutdown mode, floating or connected to 2V for the synchronous mode. 16 TON VIN sensing input. A resistor connects from this pin to VIN will set the fre- quency. A 1nF capacitor from this pin to GND is recommended to ensure the proper operation. PAD GND Power ground. Rev. 2.3 03/19/09 PIN DESCRIPTION NX2139A 5 ...
Page 6
... VREF=0.75V start soft start VCC 1M ENSW /MODE(15) MODE 1M SELECTION OVP GND(17 PAD) PGOOD(4) LDOFBUVLO_latch LDOPG(5) LDO_POR LDOFBUVLO_latch ENLDO(14) LDO_EN Figure 2 - Simplified block diagram of the NX2139A Rev. 2.3 03/19/09 4.3/4.1 Disable_B POR Thermal shutdown start ODB HD FET Driver R HD_IN Q S Mini offtime 400ns POR ...
Page 7
... VCC 13 BST LDRV ENSW 15 /MODE 10 OCSET 1 VOUT LDODRV 14 R8 ENLDO 33n R3 6 100k LDOFB 5 LDOPG GND PAD NX2139A R4 1MEG VIN 7V~22V CI1 2x10uF M1 IRF7807 2 Vout 1.8V/7A 1u 1.5uH CO1 2R5TPE330MC M2 330uF AO4714 R12 2 1. 10.5k 330p R7 M3 7.5k SI4800 1.5V@2A C5 ...
Page 8
... R7,R10,R11 R12,R13 Rev. 2.3 03/19/09 Value Manufacture 10uF/25V/X5R 10uF/6.3V/X5R 2R5TPE330MC SANYO 1uF 1nF 33nF 1.5nF 330pF DO5010H-152 COILCRAFT IRF7807 IR AO4714 AOS SI4800 PHILIPS 100k 10.5k 7.5k 50 20k 2.2 NX2139A NEXSEM INC. NX2139A 8 ...
Page 9
... Fig.8 Start into short (CH1 VIN, CH2 5V VCC, CH4 INDUCTOR CURRENT) Rev. 2.3 03/19/09 Fig.5 Turn off (CH1 1.8V OUTPUT, CH2 1.5V LDO, CH3 SW PGOOD, CH4 LDO PGOOD) Fig.7 SW output transient (CH1 1.8V OUTPUT AC, CH2 1.5V LDO AC, CH4 1.8V OUTPUT CURRENT) Fig. 9 VOUT ripple @ VIN=12V,IOUT=4A (CH1 SW, CH3 VOUT AC) NX2139A 9 ...
Page 10
... Rev. 2.3 03/19/09 VIN=12V, VOUT=1.8V 100 1000 OUTPUT CURRENT(mA) Fig. 10 Output efficiency NX2139A 10000 10 ...
Page 11
... Input voltage Output voltage OUT I - Output current OUT DV - Output voltage ripple RIPPLE F - Working frequency Inductor current ripple RIPPLE Design Example The following is typical application for NX2139A, the schematic is figure 22V IN V =1.8V OUT F =220kHz S I =7A OUT DV <=60mV RIPPLE DV < ...
Page 12
... The selected inductor is 1.5uH which is smaller ...(8) than critical inductance. In that case, the output volt- OUT age transient mainly dependent on the ESR. number of capacitor is ESR ...(9 N crit 12m 60mV 0.6 Choose N=1. NX2139A V ESR C V OUT OUT E E OUT I I step step and C represents ESR and capaci- ...
Page 13
... One 10uF/X5R/25V and two 4.7uF/ X5R/25V ceramic capacitors are chosen as input capacitors. Power MOSFETs Selection The NX2139A requires at least two N-Channel power MOSFETs. The selection of MOSFETs is based on maximum drain source voltage, gate source volt- age, maximum current rating, MOSFET on resistance Rev ...
Page 14
... PFM mode, CCM mode and shutdown mode by applying different voltage on ENSW/MODE pin. When VCC applied to ENSW /MODE pin, NX2139A is In PFM mode. The low side MOSFET emu- lates the function of diode when discontinuous con- tinuous mode happens, often in light load condition. ...
Page 15
... When the FB pin voltage is sensed over 112 the high side MOSFET will be turned off REF and low side MOSFET will be turned on to discharge the V . NX2139A resumes its switching operation af- OUT ter FB pin voltage drops REF If FB pin voltage keeps rising and is sensed over ...
Page 16
... Drain of the low-side MOSFET and source of the high-side MOSFET need to be connected thru a plane and as close as possible. A snubber needs to be placed as close to this junction as possible. NX2139A , the IC goes into latch mode. The IC will need to be practi- , REF 16 ...
Page 17
... These two grounds must be con- nected together on the PC board layout at a single point. The goal is to localize the high current path to a sepa- rate loop that does not interfere with the more sensi- tive analog control function. Rev. 2.3 03/19/09 NX2139A 17 ...
Page 18
... C16 1u R6 VCC VCC 10 LDOIN LDOIN LDODRV M3 4 SI4800 R18 LDOOUT 50 LDOOUT C19 C7 C3 33n 10u 10u R19 7.5k R20 7.5k Figure 14 - NX2139A schematic for the demoboard layout Rev. 2.3 03/19/ BST 4 2.2 PGOOD CIN1 5 LIN_PGOOD 10u/25V C17 1u 9 VCCP ...
Page 19
... Demoboard Layout Rev. 2.3 03/19/09 Figure 15 Top layer Figure 16 Ground layer NX2139A 19 ...
Page 20
... Rev. 2.3 03/19/09 Figure 17 Power layer Figure 18 Bottom layer NX2139A 20 ...
Page 21
... MAX 0.700 0.800 0.000 0.050 0.203REF 0.180 0.300 2.950 3.050 1.600 1.750 2.950 3.050 1.600 1.750 0.50BSC 0.325 0.450 1.5REF NX2139A Dimensions In Inches MIN MAX 0.028 0.031 0.000 0.002 0.008REF 0.007 0.012 0.116 0.120 0.063 0.069 0.116 0.120 0.063 0.069 0.50BSC ...