View NCP1411DMR_287260.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

NCP1411 Sync-Rect PFM Step-Up DC-DC Converter with Low-Battery Detector and Ring-Killer
NCP1411 is a monolithic micropower high frequency Boost (step-up) voltage switching converter IC specially designed for battery operated hand-held electronic products up to 250 mA loading. It integrates Synchronous Rectifier for improving efficiency as well as eliminating the external Schottky Diode. High switching frequency (up to 600 kHz) allows low profile inductor and output capacitor being used. Low-Battery Detector, Logic-Controlled Shutdown and Cycle-by-Cycle Current Limit provide value-added features for various battery-operated applications. The innovative Ring-Killer circuitry guarantees quiet operation in discontinuous conduction mode. With all these functions ON, the device quiescent supply current is only 9.0 mA typical. This device is available in the space saving compact Micro8t package.
Features http://onsemi.com MARKING DIAGRAM
8 1
Micro8 DM SUFFIX CASE 846A
A2 AYW
A2 A Y W
= Device Marking = Assembly Location = Year = Work Week
* * * * * * * * * * * * * * * * * * * *
Pb-Free Package is Available High Efficiency, up to 92% Very Low Device Quiescent Supply Current of 9.0 mA Typical Built-in Synchronous Rectifier (P-FET) Eliminates One External Schottky Diode High Switching Frequency (up to 600 kHz) Allows use of Small Size Inductor High Accuracy Reference Output, 1.19 V $ 0.6% @ 25C, can supply more than 2.5 mA when VOUT 3.3 V Ring-Killer for Quiet Operation in Discontinuous Conduction Mode 1.0 V Startup at No Load Guaranteed Output Voltage from 1.5 V to 5.5 V Adjustable Output Current up to 250 mA @ VIN = 2.5 V, VOUT = 3.3 V Logic-Controlled Shutdown Open Drain Low-Battery Detector Output 1.0 A Cycle by Cycle Current Limit Low Profile and Minimum External Parts Compact Micro8 Package
PIN CONNECTIONS
FB 1 LBI/EN 2 LBO 3 REF 4 (Top View) 8 OUT 7 LX 6 GND 5 BAT
ORDERING INFORMATION
Device NCP1411DMR2 NCP1411DMR2G Package Micro8 Micro8 (Pb-Free) Shipping 4000 Tape & Reel 4000 Tape & Reel
Typical Applications
Personal Digital Assistant (PDA) Handheld Digital Audio Product Camcorder and Digital Still Camera Handheld Instrument Conversion from One or Two NiMH or NiCd, or One Li-ion Cell to 3.3 V/5.0 V
For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D.
(c) Semiconductor Components Industries, LLC, 2004
1
October, 2004 - Rev. 3
Publication Order Number: NCP1411/D
NCP1411
Input 1 V to VOUT
10 mF
22 mH
220 pF 200 k Low Battery Sense Input Shutdown Open Drain Input Low Battery Open Drain Output
150 pF
350 k 1 2 FB
NCP1411 OUT LX GND BAT 8 7 6 5 33 mF + Output 1.5 to 5.5 V IOUT Typical Up to 250 mA at 3.3 V Output and 2.5 V Input
RLB1
RLB2
LBI/EN LBO REF
3 4
CEN 120 nF
150 nF
Figure 1. Typical Operating Circuit
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
PIN FUNCTION DESCRIPTION
Pin # 1 2 3 4 5 6 7 8 Symbol FB Pin Description Output Voltage Feedback Input. LBI/EN LBO REF BAT GND LX OUT Low-Battery Detector Input and IC Enable. Open-Drain Low-Battery Detector Output. Output is LOW when VLBI is < 1.178 V. LBO is high impedance during shutdown. 1.190 V Reference Voltage Output, bypassing with 150 nF capacitor if this pin is not loaded, bypassing with 1.0 mF if this pin is loaded up to 2.5 mA @ VOUT = 3.3 V. Battery input connection for internal Ring-Killer. Ground. N-Channel and P-Channel Power MOSFET Drain Connection. Power Output. OUT also provides bootstrapped power to the device.
MAXIMUM RATINGS
Rating Device Power Supply (Pin 8) Input/Output Pins (Pins 1-5, Pin 7) Thermal Characteristics - Micro8 Plastic Package Maximum Power Dissipation @ TA = 25C Thermal Resistance, Junction-to-Air Operating Junction Temperature Range Operating Ambient Temperature Range Storage Temperature Range Symbol VOUT VIO PD RqJA TJ TA Tstg Value -0.3 to 6.0 -0.3 to 6.0 520 240 -40 to +150 -40 to +85 -55 to +150 Unit V V mW C/W C C C
Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied, damage may occur and reliability may be affected. 1. This device contains ESD protection and exceeds the following tests: Human Body Model (HBM) "2.0 kV per JEDEC standard: JESD22-A114. Machine Model (MM) "200 V per JEDEC standard: JESD22-A115. 2. The maximum package power dissipation limit must not be exceeded. PD + TJ(max) * TA RqJA
3. Latchup Current Maximum Rating: "150 mA per JEDEC standard: JESD78. 4. Moisture Sensitivity Level: MSL 1 per IPC/JEDEC standard: J-STD-020A.
http://onsemi.com
2
NCP1411
ELECTRICAL CHARACTERISTICS (VOUT = 3.3 V, TA = 25C for typical value, -40C TA 85C for min/max values
unless otherwise noted.) Characteristic Operating Input Voltage Output Voltage Range (Adjusted by external feedback) Reference Voltage (CREF = 150 nF, under no loading, TA = 25C) Reference Voltage (CREF = 150 nF, under no loading, -40C TA 85C) Reference Voltage Temperature Coefficient Reference Voltage Load Current (VOUT = 3.3 V, VREF = VREF_NL 1.5%, CREF = 1.0 mF) (Note 5) Reference Voltage Load Regulation (VOUT = 3.3 V, ILOAD = 0 to 100 mA, CREF = 1.0 mF) Reference Voltage Line Regulation (VOUT from 1.5 V to 5.5 V, CREF = 1.0 mF) FB, LBI Input Threshold (ILOAD = 0 mA) N-FET ON Resistance P-FET ON Resistance LX Switch Current Limit (N-FET) Operating Current into OUT (VFB = 1.4 V, i.e. no switching, VOUT = 3.3 V) Shutdown Current into OUT (LBI/EN = GND) LX Switch MAX. ON-Time (VFB = 1.0 V, VOUT = 3.3 V) LX Switch MIN. OFF-Time (VFB = 1.0 V, VOUT = 3.3 V) FB Input Current Shutdown Current into BAT (LBI/EN = 0 V, VOUT = VBAT = 3.0 V) BAT to LX resistance (VFB = 1.4 V, VOUT = 3.3 V) LBI/EN Input Current LBO Low Output Voltage (VLBI = 0 V, ISINK = 1.0 mA) ENABLE (Pin 2) Input threshold, Low ENABLE (Pin 2) Input threshold, High 5. Loading capability increases with VOUT. Symbol VIN VOUT VREF_NL VREF_NL_A TCVREF IREF VREF_LOAD VREF_LINE VFB, VLBI RDS(ON)-N RDS(ON)-P ILIM IQ ISD tON tOFF IFB ILBT RLBT_LX ILBI/EN VLBO_L VEN VEN Min 1.0 VIN 1.183 1.178 - 2.5 - - 1.174 - - - - - 1.2 0.25 - - - - - - 0.6 Typ - - 1.190 - 0.03 - 0.015 0.03 1.190 0.6 0.9 1.0 9.0 0.05 1.4 0.31 1.5 50 100 1.5 - - - Max 5.5 5.5 1.197 1.202 - - 1.0 1.0 1.200 - - - 14 1.0 1.8 0.37 9.0 - - 8.0 0.05 0.3 - Unit V V V V mV/C mA mV mV/V V W W A mA mA mS mS nA nA W nA V V V
http://onsemi.com
3
NCP1411
VBAT M3 BAT 5
ZLC Chip Enable
+ -
+ 20 mV
VDD M2
LX 7 OUT 8
VOUT
CONTROL LOGIC _ZCUR _MSON _MAINSW2ON _PWQONCE _CEN _PFM _MAINSWOFD _SYNSW2ON VDD SENSEFET M1
FB 1
+ - PFM
GND
6 VDD GND
REF 4
Voltage Reference
_SYNSWOFD _VREFOK _ILIM ILIM + - + -
GND
RSENSE + GND LBO 3
LBI/EN 2
GND
Figure 2. Simplified Functional Diagram
http://onsemi.com
4
NCP1411
TYPICAL OPERATING CHARACTERISTICS
1.220 VREF, REFERENCE VOLTAGE (V) 1.215 1.210 1.205 VIN = 2.2 V 1.200 1.195 VIN = 3.0 V 1.190 1 10 100 ILOAD, OUTPUT CURRENT (mA) 1000 VREF, REFERENCE VOLTAGE (V) VOUT = 3.3 V L = 22 mH CIN = 10 mF COUT = 33 mF CREF = 1 mF TA = 25C 1.195
VIN = 1.8 V
1.192 IREF = 0 mA 1.189
1.186 CREF = 1 mF TA = 25C
IREF = 2.5 mA
1.183 1.180 1
2 3 4 5 VOUT, INPUT VOLTAGE AT OUT PIN (V)
6
Figure 3. Reference Voltage versus Output Current
Figure 4. Reference Voltage versus Input Voltage at OUT Pin
1.192
RDS(on), SWITCH ON RESISTANCE (W)
1.194 VREF, REFERENCE VOLTAGE (V)
1.5
1.2 P-FET (M2) 0.9 N-FET (M1)
1.190
1.188 VOUT = 3.3 V CREF = 150 nF IREF = 0 mA -20 0 20 40 60 80 TA, AMBIENT TEMPERATURE (C) 100
0.6
1.186 1.184 -40
0.3 VOUT = 3.3 V 0 -40 -20 40 60 80 0 20 TA, AMBIENT TEMPERATURE (C) 100
Figure 5. Reference Voltage versus Temperature
VBATT, MIN. STARTUP BATTERY VOLTAGE (V)
Figure 6. Switch ON Resistance versus Temperature
1.8 LX, SWITCH MAX. ON TIME (ton/mS) 1.7 1.6 1.5 1.4 1.3 1.2 -40
1.9 WITHOUT SCHOTTKY DIODE 1.6
1.4
1.1
WITH SCHOTTKY DIODE (MBR0502)
0.9 0.6 0 20 100 40 60 80 ILOAD, OUTPUT LOADING CURRENT (mA) 120
-20
20 60 80 0 40 TA, AMBIENT TEMPERATURE (C)
100
Figure 7. LX Switch Max. ON Time versus
Temperature
Figure 8. Min. Startup Battery Voltage versus Loading Current
http://onsemi.com
5
NCP1411
100 L = 22 mH EFFICIENCY (%) 100
90 EFFICIENCY (%)
90
L = 27 mH L = 22 mH
80
L = 10 mH
L = 15 mH
80
70 VIN = 1.8 V VOUT = 3.3 V CIN = 10 mF COUT = 33 mF 1 10 100 ILOAD, OUTPUT LOADING CURRENT (mA) 1000
70 VIN = 2.2 V VOUT = 5 V CIN = 10 mF COUT = 33 mF 1 10 100 ILOAD, OUTPUT LOADING CURRENT (mA) 1000
60 50
60 50
Figure 9. Efficiency versus Load Current
Figure 10. Efficiency versus Load Current
100 L = 22 mH L = 10 mH L = 15 mH EFFICIENCY (%)
100 L = 27 mH L = 22 mH 80
90 EFFICIENCY (%)
90
80
70 VIN = 2.2 V VOUT = 3.3 V CIN = 10 mF COUT = 33 mF 1 10 100 ILOAD, OUTPUT LOADING CURRENT (mA) 1000
70 VIN = 2.2 V VOUT = 3.3 V CIN = 10 mF COUT = 33 mF 1 10 100 ILOAD, OUTPUT LOADING CURRENT (mA) 1000
60 50
60 50
Figure 11. Efficiency versus Load Current
Figure 12. Efficiency versus Load Current
100 L = 22 mH 90 EFFICIENCY (%) L = 10 mH L = 15 mH EFFICIENCY (%)
100 L = 27 mH 90 L = 22 mH 80
80
70 VIN = 3 V VOUT = 3.3 V CIN = 10 mF COUT = 33 mF 1 10 100 ILOAD, OUTPUT LOADING CURRENT (mA) 1000
70 VIN = 4.5 V VOUT = 5 V CIN = 10 mF COUT = 33 mF 1 10 100 ILOAD, OUTPUT LOADING CURRENT (mA) 1000
60 50
60 50
Figure 13. Efficiency versus Load Current
Figure 14. Efficiency versus Load Current
http://onsemi.com
6
NCP1411
3.0 2.0 1.0 3V 0 2.2 V L = 22 mH VOUT = 3.3 V CIN = 10 mF COUT = 33 mF 1 VIN = 1.8 V OUTPUT VOLTAGE CHANGE (%) OUTPUT VOLTAGE CHANGE (%) 3.0 2.0 1.0 0 -1.0 -2.0 -3.0 1000 1 3V
-1.0 -2.0
-3.0
L = 15 mH VOUT = 3.3 V CIN = 10 mF COUT = 33 mF
2.2 V VIN = 1.8 V
10 100 ILOAD, OUTPUT LOADING CURRENT (mA)
10 100 ILOAD, OUTPUT LOADING CURRENT (mA)
1000
Figure 15. Output Voltage Change versus Load Current
200 VRIPPLE, RIPPLE VOLTAGE (mVp-p) VOUT = 3.3 V CIN = 10 mF COUT = 33 mF L = 22 mH VRIPPLE, RIPPLE VOLTAGE (mVp-p) 200
Figure 16. Output Voltage Change versus Load Current
160
160
200 mA
VOUT = 3.3 V CIN = 10 mF COUT = 33 mF L = 15 mH
120 200 mA 100 mA 40 0 1 2.5 1.5 2 VBATT, BATTERY INPUT VOLTAGE (V) 3
120 100 mA
80
80
40 0 1 1.5 2 2.5 VBATT, BATTERY INPUT VOLTAGE (V) 3
Figure 17. Battery Input Voltage versus Output Ripple Voltage
IBATT, NO LOAD OPERATING CURRENT (mA)
Figure 18. Battery Input Voltage versus Output Ripple Voltage
20
16
12
8
4 0 0 1 4 5 6 2 3 VOUT, INPUT VOLTAGE AT OUT PIN (V) 7
(VIN = 2.2 V, VOUT = 3.3 V, ILOAD = 100 mA; L = 22 mH, COUT = 33 mF)
Figure 19. No Load Operating Current versus Input Voltage at OUT Pin
Upper Trace: Output Voltage Waveform, 2.0 V/Division Lower Trace: Shutdown Pin Waveform, 1.0 V/Division
Figure 20. Startup Transient Response
http://onsemi.com
7
NCP1411
(VIN = 2.2 V, VOUT = 3.3 V, ILOAD = 100 mA; L = 22 mH, COUT = 33 mF)
(VIN = 2.2 V, VOUT = 3.3 V, ILOAD = 30 mA; L = 22 mH, COUT = 33 mF)
Upper Trace: Voltage at LX pin, 2.0 V/Division MiddleTrace: Output Voltage Ripple, 50 mV/Division Lower Trace: Inductor Current, IL, 100 mA/Division
Upper Trace: Voltage at LX pin, 2.0 V/Division MiddleTrace: Output Voltage Ripple, 50 mV/Division Lower Trace: Inductor Current, IL, 100 mA/Division
Figure 21. Continuous Conduction Mode Switching Waveform
Figure 22. Discontinuous Conduction Mode Switching Waveform
(VIN = 1.8 V to 3.0 V, L = 22 mH, COUT = 33 mF)
(VOUT = 3.3 V, ILOAD = 10 mA to 100 mA; L = 22 mH, COUT = 33 mF)
Upper Trace: Output Voltage Ripple, 100 mV/Division Lower Trace: Battery Voltage, VIN, 1.0 V/Division
Upper Trace: Output Voltage Ripple, 100 mV/Division Lower Trace: Load Current, ILOAD, 50 mA/Division
Figure 23. Line Transient Response for VOUT = 3.3 V
Figure 24. Load Transient Response for VIN = 1.8 V
(VOUT = 3.3 V, ILOAD = 10 mA to 100 mA; L = 22 mH, COUT = 33 mF)
(VOUT = 3.3 V, ILOAD = 10 mA to 100 mA; L = 22 mH, COUT = 33 mF)
Upper Trace: Output Voltage Ripple, 100 mV/Division Lower Trace: Load Current, ILOAD, 50 mA/Division
Upper Trace: Output Voltage Ripple, 100 mV/Division Lower Trace: Load Current, ILOAD, 50 mA/Division
Figure 25. Load Transient Response for VIN = 2.4 V http://onsemi.com
8
Figure 26. Load Transient Response for VIN = 3.3 V
NCP1411
DETAILED OPERATION DESCRIPTIONS NCP1411 is a monolithic micropower high frequency step-up voltage switching converter IC specially designed for battery operated hand-held electronic products up to 250 mA loading. It integrates Synchronous Rectifier for improving efficiency as well as eliminating the external Schottky Diode. High switching frequency (up to 600 kHz) allows low profile inductor and output capacitor being used. Low-Battery Detector, Logic-Controlled Shutdown and Cycle-by-Cycle Current Limit provide value-added features for various battery-operated application. With all these functions ON, the quiescent supply current is only 9.0 mA typical. This device is available in a compact Micro8 package.
PFM Regulation Scheme
From the simplified Functional Diagram (Figure 2), the output voltage is divided down and fed back to pin 1 (FB). This voltage goes to the non-inverting input of the PFM comparator whereas the comparator's inverting input is connected to REF. A switching cycle is initiated by the falling edge of the comparator, at the moment, the main switch (M1) is turned ON. After the maximum ON-time (typical 1.4 mS) elapses or the current limit is reached, M1 is turned OFF, and the synchronous switch (M2) is turned ON. The M1 OFF time is not less than the minimum OFF-time (typical 0.31 mS), this is to ensure energy transfer from the inductor to the output capacitor. If the regulator is operating at Continuous Conduction Mode (CCM), M2 is turned OFF just before M1 is supposed to be ON again. If the regulator is operating at Discontinuous Conduction Mode (DCM), which means the coil current will decrease to zero before the next cycle, M1 is turned OFF as the coil current is almost reaching zero. The comparator (ZLC) with fixed offset is dedicated to sense the voltage drop across M2 as it is conducting, when the voltage drop is below the offset, the ZLC comparator output goes HIGH, and M2 is turned OFF. Negative feedback of closed loop operation regulates voltage at pin 1 (FB) equal to the internal voltage reference (1.190 V).
Synchronous Rectification
situation will occur. So dead time is introduced to make sure M2 is completely turned OFF before M1 is being turned ON. When the regulator is operating in DCM, as coil current is dropped to zero, M2 is supposed to be OFF. Fail to do so, reverse current will flow from the output bulk capacitor through M2 and then the inductor to the battery input. It causes damage to the battery. So the ZLC comparator comes with fixed offset voltage to switch M2 OFF before any reverse current builds up. However, if M2 is switch OFF too early, large residue coil current flows through the body diode of M2 and increases conduction loss. Therefore, determination on the offset voltage is essential for optimum performance. With the implementation of synchronous rectification, efficiency can be as high as 92%. For single cell input voltage, use an external Schottky diode such as MBR0520 connected from pin 7 to pin 8 to ensure quick startup.
Ring-Killer
When the device entered Discontinuous Conduction Mode operation, a typical ringing at LX pin will start while the inductor current just ceased. This ringing is caused primarily by the capacitance and inductance at LX node and the result can produce unwanted EMI problem to the system. In order to eliminate this ringing, an internal damping switch (M3) is implemented to provide a low impedance path to dissipate the residue energy stored in the inductor once the operation entered the Discontinuous Conduction Mode. This feature can improve the EMI problem. The performance of the Ring-Killer switch is shown in Figure 22.
Cycle-by-Cycle Current Limit
Synchronous Rectifier is used to replace Schottky Diode for eliminating the conduction loss contributed by forward voltage of the latter. Synchronous Rectifier is normally realized by powerFET with gate control circuitry which, however, involved relative complicated timing concerns. As main switch M1 is being turned OFF, if the synchronous switch M2 is just turned ON with M1 not being completed turned OFF, current will be shunt from the output bulk capacitor through M2 and M1 to ground. This power loss lowers overall efficiency. So a certain amount of dead time is introduced to make sure M1 is completely OFF before M2 is being turned ON. When the main regulator is operating in CCM, as M2 is being turned OFF, and M1 is just turned ON with M2 not being completely turned OFF, the above mentioned
From Figure 2, SENSEFET is applied to sample the coil current as M1 is ON. With that sample current flowing through a sense resistor, sense-voltage is developed. Threshold detector (ILIM) detects whether the sense-voltage is higher than preset level. If it happens, detector output signifies the CONTROL LOGIC to switch OFF M1, and M1 can only be switched ON as next cycle starts after the minimum OFF-time (typical 0.31 mS). With properly sizing of SENSEFET and sense resistor, the peak coil current limit is set at 1.0 A typically.
Voltage Reference
The voltage at REF is set typically at +1.190 V. It can deliver up to 2.5 mA with load regulation 1.5%, at VOUT equal to 3.3 V. If VOUT is increased, the REF load capability can also be increased. A bypass capacitor of 0.15 mF is required for proper operation when REF is not loaded. If REF is loaded, 1.0 mF capacitor at REF is needed.
Shutdown
The IC will shutdown when the voltage at pin 2 (LBI/EN) is pulled lower than 0.3 V. During shutdown, M1 and M2 are both switched OFF, however, the body diode of M2 allows current flow from battery to the output, the IC internal circuit will consume less than 0.05 mA current typically. If the
http://onsemi.com
9
NCP1411
pin 1 voltage raised higher than 0.6 V, the IC will be enabled. The internal circuit will only consume 9.0 mA current typically from the OUT pin. In order to ensure proper startup, a timing capacitor CEN as shown in Figure 1 is required to provide the reset pulse during batteries are plugged in. The product of RLB1 and CEN must be larger than 28 msec.
Low-Battery Detection
time. One other parameter of the inductor is its DC resistance, this resistance can introduce unwanted power loss and hence reduce overall efficiency, the basic rule is selecting an inductor with lowest DC resistance within the board space limitation of the end application.
Capacitors Selection
A comparator with 30 mV hysteresis is applied to perform the low-battery detection function. When pin 2 (LBI/EN) is at a voltage, which can be defined by a resistor divider from the battery voltage, lower than the internal reference voltage, 1.190 V, the comparator output will cause a 50 Ohm low side switch to be turned ON. It will pull down the voltage at pin 3 (LBO) which has a hundreds kilo-Ohm of pull-high resistance. If the pin 2 voltage is higher than 1.190 V +30 mV, the comparator output will cause the 50 Ohm low side switch to be turned OFF, pin 3 will become high impedance, and its voltage will be pulled high. APPLICATIONS INFORMATION
Output Voltage Setting
In all switching mode boost converter applications, both the input and output terminals sees impulsive voltage/current waveforms. The currents flowing into and out of the capacitors multiplying with the Equivalent Series Resistance (ESR) of the capacitor producing ripple voltage at the terminals. During the syn-rect switch off cycle, the charges stored in the output capacitor is used to sustain the output load current. Load current at this period and the ESR combined and reflected as ripple at the output terminal. For all cases, the lower the capacitor ESR, the lower the ripple voltage at output. As a general guide line, low ESR capacitors should be used. Ceramic capacitors have the lowest ESR, but low ESR tantalum capacitors can also be used as a cost effective substitute.
Optional Startup Schottky Diode for Low Battery Voltage
The output voltage of the converter is determined by the external feedback network comprised of RFB1 and RFB2 and the relationship is given by:
VOUT + 1.190 V R 1 ) FB1 RFB2
where RFB1 and RFB2 are the upper and lower feedback resistors respectively.
Low Battery Detect Level Setting
In general operation, no external schottky diode is required, however, in case you are intended to operate the device close to 1.0 V level, a schottky diode connected between the LX and OUT pins as shown in Figure 27 can help during startup of the converter. The effect of the additional schottky was shown in Figure 8.
L MBR0502 VOUT
The Low Battery Detect Voltage of the converter is determined by the external divider network comprised of RLB1 and RLB2 and the relationship is given by:
VLB + 1.190 V R 1 ) LB1 RLB2
NCP1411
OUT COUT LX
where RLB1 and RLB2 are the upper and lower divider resistors respectively.
Inductor Selection Figure 27. PCB Layout Recommendations
The NCP1411 is tested to produce optimum performance with a 22 mH inductor at VIN = 3.0 V, VOUT = 3.3 V supplying output current up to 250 mA. For other input/output requirements, inductance in the range 10 mH to 47 mH can be used according to end application specifications. Selecting an inductor is a compromise between output current capability and tolerable output voltage ripple. Of course, the first thing we need to obey is to keep the peak inductor current below its saturation limit at maximum current and the ILIM of the device. In NCP1411, ILIM is set at 1.0 A. As a rule of thumb, low inductance values supply higher output current, but also increase the ripple at output and reducing efficiency, on the other hand, high inductance values can improve output ripple and efficiency, however it also limit the output current capability at the same
PCB Layout Recommendations
Good PCB layout plays an important role in switching mode power conversion. Careful PCB layout can help to minimize ground bounce, EMI noise and unwanted feedback that can affect the performance of the converter. Hints suggested in below can be used as a guide line in most situations.
Grounding
Star-ground connection should be used to connect the output power return ground, the input power return ground and the device power ground together at one point. All high current running paths must be thick enough for current flowing through and producing insignificant voltage drop
http://onsemi.com
10
NCP1411
along the path. Feedback signal path must be separated with the main current path and sensing directly at the anode of the output capacitor.
Components Placement
kept away from the feedback (FB, pin 1) terminal to avoid unwanted injection of noise into the feedback path.
Feedback Network
Power components, i.e. input capacitor, inductor and output capacitor, must be placed as close together as possible. All connecting traces must be short, direct and thick. High current flowing and switching paths must be
Feedback of the output voltage must be a separate trace detached from the power path. External feedback network must be placed very close to the feedback (FB, pin 1) pin and sensing the output voltage directly at the anode of the output capacitor.
RFB1 335 k VBATT RLB1 225 k CIN 10 mF/10 V + CEN 120 nF RLB2 330 k GND CFB2 220 pF RFB2 200 k
CFB1 150 pF
L 22 mH NCP1411
VOUT
1 2 3 4 CREF 150 nF
FB LBI/EN LBO REF
OUT LX GND BAT
8 7 6 5 + COUT 33 mF/10 V
GND
Figure 28. Typical Application Schematic for 2 Alkaline Cells Supply
http://onsemi.com
11
NCP1411
GENERAL DESIGN PROCEDURES Switching mode converter design is considered as black magic to most engineers, some complicate empirical formulae are available for reference usage. Those formulae are derived from the assumption that the key components, i.e. power inductor and capacitors are available with no tolerance. Practically, its not true, the result is not a matter of how accurate the equations you are using to calculate the component values, the outcome is still somehow away from the optimum point. In below a simple method base on the most basic first order equations to estimate the inductor and capacitor values for NCP1411 operate in Continuous Conduction Mode is introduced. The component value set can be used as a starting point to fine tune the circuit operation. By all means, detail bench testing is needed to get the best performance out of the circuit. Design Parameters: VIN = 1.8 V to 3.0 V, Typical 2.4 V VOUT = 3.3 V IOUT = 200 mA (250 mA max) VLB = 2.0 V VOUT-RIPPLE = 40 mVP-P at IOUT = 250 mA Calculate the feedback network: Select RFB2 = 200 K
V RFB1 + RFB2 OUT * 1 VREF RFB1 + 200 K 3.3 V * 1 + 355 K 1.19 V RLB1 + RLB2 RLB1 + 330 K VLB *1 VREF
2.0 V * 1 + 225 K 1.19 V
CEN + 28 msec + 120 nF 225 K
Determine the Steady State Duty Ratio, D for typical VIN, operation will be optimized around this point:
VOUT +1 VIN 1*D D+1* VIN + 1 * 2.4 V + 0.273 3.3 V VOUT
Determine the average inductor current, ILAVG at maximum IOUT:
I ILAVG + OUT + 250 mA + 344 mA 1 * 0.273 1*D
Determine the peak inductor ripple current, IRIPPLE-P and calculate the inductor value: Assume IRIPPLE-P is 20% of ILAVG, the inductance of the power inductor can be calculated as in below: IRIPPLE-P = 0.20 x 344 mA = 68.8 mA
L+ VIN tON 2.4 V 1.4 mS + + 24.4 mH 2(68.8 mA) 2IRIPPLE-P
Standard value of 22 mH is selected for initial trial. Determine the output voltage ripple, VOUT-RIPPLE and calculate the output capacitor value: VOUT-RIPPLE = 40 mVP-P at IOUT = 250 mA
COUT w IOUT tON VOUT * RIPPLE * IOUT ESRCOUT
With the feedback resistor divider, additional small capacitor, CFB1 in parallel with RFB1 is required to ensure stability. The value can be in between 68 pF to 220 pF, the rule is to select the lowest capacitance to ensure stability. Also a small capacitor, CFB2 in parallel with RFB2 may also be needed to lower the feedback ripple hence improve output regulation. The use of CFB2 is a compromise between output ripple level and regulation, so careful selection of the value according to end application requirement is needed. In this example, values for CFB1 and CFB2 are 150 pF and 220 pF respectively. Calculate the Low Battery Detect divider: VLB = 2.0 V Select RLB2 = 330 K
where tON = 1.4 mS and ESRCOUT = 0.1 W,
COUT w 250 mA 1.4 mS + 23.33 mF 40 mV * 250 mA 0.1 W
From above calculation, we need at least 23.33 mF in order to achieve the specified ripple level at conditions stated. Practically, a one level larger capacitor will be used to accommodate factors not take into account in the calculation. So a capacitor value of 33 mF is selected.
http://onsemi.com
12
NCP1411
PACKAGE DIMENSIONS
Micro8 DM SUFFIX CASE 846A-02 ISSUE F
-A-
K
-B-
PIN 1 ID
G D 8 PL 0.08 (0.003)
M
NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSION A DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.15 (0.006) PER SIDE. 4. DIMENSION B DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. INTERLEAD FLASH OR PROTRUSION SHALL NOT EXCEED 0.25 (0.010) PER SIDE. 5. 846A-01 OBSOLETE, NEW STANDARD 846A-02. DIM A B C D G H J K L MILLIMETERS MIN MAX 2.90 3.10 2.90 3.10 --- 1.10 0.25 0.40 0.65 BSC 0.05 0.15 0.13 0.23 4.75 5.05 0.40 0.70 INCHES MIN MAX 0.114 0.122 0.114 0.122 --- 0.043 0.010 0.016 0.026 BSC 0.002 0.006 0.005 0.009 0.187 0.199 0.016 0.028
TB
S
A
S
-T- PLANE 0.038 (0.0015) H
SEATING
C J L
SOLDERING FOOTPRINT*
8X
1.04 0.041
0.38 0.015
8X
3.20 0.126
4.24 0.167
5.28 0.208
6X
0.65 0.0256
SCALE 8:1
mm inches
*For additional information on our Pb-Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D.
http://onsemi.com
13
NCP1411
Micro8 is a trademark of International Rectifier.
ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. "Typical" parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.
PUBLICATION ORDERING INFORMATION
LITERATURE FULFILLMENT: Literature Distribution Center for ON Semiconductor P.O. Box 61312, Phoenix, Arizona 85082-1312 USA Phone: 480-829-7710 or 800-344-3860 Toll Free USA/Canada Fax: 480-829-7709 or 800-344-3867 Toll Free USA/Canada Email: orderlit@onsemi.com N. American Technical Support: 800-282-9855 Toll Free USA/Canada Japan: ON Semiconductor, Japan Customer Focus Center 2-9-1 Kamimeguro, Meguro-ku, Tokyo, Japan 153-0051 Phone: 81-3-5773-3850 ON Semiconductor Website: http://onsemi.com Order Literature: http://www.onsemi.com/litorder For additional information, please contact your local Sales Representative.
http://onsemi.com
14
NCP1411/D

▲Up To Search▲

Price & Availability of NCP1411DMR

	To Download NCP1411DMR Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .