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NCP1500 Dual Mode PWM/Linear BUCK Converter
The NCP1500 is a dual mode converter that operates as either a pulse width modulated (PWM) buck converter or as a linear regulator. The converter automatically transitions between the two modes. The converter operates as a PWM when a synchronization signal is present at the sync input. The converter operates as a linear regulator in the absence of a synchronization signal. The PWM mode offers excellent performance at normal to heavy loads at the sacrifice of output ripple voltage. The linear mode offers excellent noise rejection at the sacrifice of system efficiency. The user is able to select which mode will give the best performance for a given operating condition. Internal protection features include thermal shutdown with hysteresis and cycle-by-cycle current limit in the PWM mode. Additionally, the converter transitions into PFM mode at very light loads if a synchronization signal is present and an output overvoltage condition is detected.
PWM Features http://onsemi.com MARKING DIAGRAM
8 8 1 Micro8t (MSOP-8) DM SUFFIX CASE 846A 1 1500 AYW
* Current Mode Control with Cycle-by-Cycle Current Limit * Nominal Synchronization Frequency of 270 to 630 kHz * Built-in Slope Compensation
Linear Regulator Features
A = Assembly Location Y = Year W = Work Week
PIN CONNECTIONS
SHD SYN VO LX 1 2 3 4 (Top View) 8 7 6 5 CB0 CB1 GND VIN
* Low Output Noise
Overall Features
* Thermal Shutdown with Hysteresis * Digitally Programmable Output Voltage Between 4 Voltages: * * * * *
1.0, 1.3, 1.5, and 1.8 Fast Transient Response Input Voltage Range From 2.7 V to 5.4 V Space Saving Micro8 Package Low Shutdown Current of 0.18 mA Typical Pb-Free Package is Available
ORDERING INFORMATION
Device NCP1500DMR2 NCP1500DMR2G Package Micro8 Micro8 (Pb-Free) Shipping 4000 Tape/Reel 4000 Tape/Reel
Typical Applications
* Baseband Supplies for Portable Handsets * PDAs * Supplies for DSP Circuitry
1 SHD 2 SYN 3 VO L COUT 4 LX MBRM120 CB0 CB1 GND VIN 8 7 6 5 CIN VIN
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.
L = 15 mH CIN = 10 mF COUT = 10 mF
Figure 1. Typical Operating Circuit
(c) Semiconductor Components Industries, LLC, 2004
1
February, 2004 - Rev. 4
Publication Order Number: NCP1500/D
NCP1500
PIN FUNCTION DESCRIPTIONS
Pin # 1 Symbol SHD Pin Description Device is placed in shutdown when SHD is driven low. In shutdown mode, the internal MOSFET and output are turned off. Driven to high for normal operation. This pin is floating internally and needs to be tied to a fixed source externally. External Synchronization Clock Signal Input. If a clock signal is present at this pin, the device will go into PWM mode. If SYN is driven low, the device operates in linear mode. Connected to internal voltage divider for feedback. Pin for the connection between the drain of the internal P-MOSFET and the external inductor. Voltage Supply Input. Bypass with 10 mF capacitor. Ground. Control Bit 1 Input for output voltage level selection. Internally pulled low. Control Bit 0 Input for output voltage level selection. Internally pulled low.
2 3 4 5 6 7 8
SYN VO LX VIN GND CB1 CB0
ABSOLUTE MAXIMUM RATINGS
Rating Power Supply (Pin 5) Input/Output Pins Pin 1-4 & Pin 7-8 Thermal Characteristics Micro8 Plastic Package Thermal Resistance Junction to Air Operating Junction Temperature Range Operating Ambient Temperature Range Storage Temperature Range 1. This device series 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. Latch-up Current Maximum Rating: $150 mA per JEDEC standard: JESD78. Symbol VIN VIO Value -0.3 to 6.0 -0.3 to 6.0 Unit V V
RqJA TJ TA Tstg
240 -40 to +140 - 40 to +85 - 55 to +150
C/W C C C
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NCP1500
ELECTRICAL CHARACTERISTICS (VIN = 3.6 V, VO = 1.5 V, TA = 25C, Fsyn = 600 kHz 50% Duty Cycle sinewave with VH = 2.0 V
and VL = 0 V for PWM mode; TA = -40 to 85C for Min/Max values, unless otherwise noted.) Characteristic Input Voltage Range Main FET Leakage Current (Pins 5 to 4) TA = 25C Main FET Leakage Current (Pins 5 to 4) TA = -40C to 85C Mode Selection Pin SYN "H" Input Voltage SYN "L" Input Voltage SYN "H" Input Current SYN "L" Input Current External Synchronization Frequency Output Level Selection Pins CB "H" Input Voltage Threshold CB "L" Input Voltage Threshold CB "H" Input Current CB "L" Input Current Shutdown Pin SHD "H" Input Voltage Threshold SHD "L" Input Voltage Threshold SHD "H" Input Current SHD "L" Input Current PWM Mode Output Voltage (IOUT = 35 mA, TA = 25C) CB0, CB1 = (H, H) CB0, CB1 = (H, L) CB0, CB1 = (L, L) CB0, CB1 = (L, H) Line Regulation, Iout = 100 mA 3.0 to 3.6 V 3.0 to 4.2 V Load Regulation 50 to 120 mA 20 to 200 mA Minimum On-Time Internal PFET ON-Resistance (ILX = 400 mA, VIN = 2.0 V) Main Output Switch Current Limit Linear Regulator Mode (Lx shorted to Vo) Output Voltage (Iout = 0 mA, TA = 25C) CB0, CB1 = (H, H) CB0, CB1 = (H, L) CB0, CB1 = (L, L) CB0, CB1 = (L, H) Startup Current Load in Linear Mode Overvoltage Protection Output Overvoltage Threshold in PWM Mode Total Device Power Supply Current Standby (SHD tied low, VIN = 3.6 V, SYN tied low) TA = 25C TA = -40C to 85C PWM Mode (SHD tied high, VIN = 3.6 V, Vout = 1.6 V, VCB0 = VCB1 = 0 V, SYN @ 600 kHz/50% duty cycle, Iout = 0 mA) Linear Mode (SHD tied high, VIN = 3.6 V, Vout = 1.5 V, SYN tied low, Iout = 0 mA) ICC - - - - 0.18 - 96 30 0.5 10 150 70 mA VOPFM - +5.0 +10 % Vout0 0.941 1.235 1.425 1.710 ISTARTLIN 80 0.99 1.30 1.50 1.80 - 1.050 1.365 1.575 1.890 - mA V VOUT0 0.941 1.235 1.425 1.710 DVout0 - - DVout0 - - TONMIN RDS(ON)_P ILIM - - - 1.0 13 210 0.65 800 - - - 1.2 - nsec W mA 1.0 2.0 - - mV 0.99 1.30 1.50 1.80 1.050 1.365 1.575 1.890 mV V VSHDH VSHDL ISHDH ISHDL 0.59 - - - - - 0.1 0 - 0.26 - - V V mA mA VCBH VCBL ICBH ICBL 0.90 - - - - - 0.1 0 - 0.63 - - V V mA mA VSYNH VSYNL ISYNH ISYNL FSYNC 1.3 - - -0.5 270 - - 0 0 - - 1.1 0.5 - 630 V V mA mA kHz Symbol VIN ILEAK Min 2.7 - - Typ - 0.06 - Max 5.4 0.3 10 Unit V mA
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NCP1500
SHD Reference Out + - ILimit PWM SYN Sync Detection and Timing Block Mode Select + Slope Compression - SoftStart - - + Out R LX MBRM120 Thermal Shutdown Linear Control Block VO + - L Output Voltage C2 Vref + 5% S Q C1 VCC Input Voltage
PWM Comparator
Out
CVP Comparator Out
+ - Vref
Error Amplifier CB0
CB1
Output Voltage Program MUX
Ground
Component C1, C2 L
Value 10 mF, 6.3 V 15 mH
Manufacturer TDK, C3216X5R0J106M TDK, RLF5018T-150MR76 (Iout = 300 mA) Coilcraft, D01606T-153 (Iout = 300 mA) TDK, NLC252018T-150 (Iout = 100 mA)
Figure 2. Typical Circuit with the Internal Schematic
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NCP1500
DETAILED OPERATING DESCRIPTION Introduction The NCP1500 is a dual mode regulator intended for use in baseband supplies for portable equipment. Its unique features provide power to the baseband circuitry while, at the same time save valuable battery energy. When the handset is idle, the user can activate the linear regulator function. In this mode, the regulator provides a regulated low current, low noise output voltage keeping the baseband circuit biased. When the handset is in its normal operating mode, the regulator synchronizes to the baseband clock and turns into a switching regulator. This allows the regulator to provide efficient power to the baseband circuit. Operating Description
Synchronization Protocol and Mode Selection
Figure 3 shows the waveform when the SYNC signal is applied. After several cycles, the MODE select changes and PWM operation is activated with the internal clock signal. Reference/Shutdown The NCP1500 uses an internal reference, typically at 0.8 V. An external shutdown pin is provided. When this pin is pulled low, the reference and other circuitry are disabled, placing the part into a low quiescent current standby mode. In this mode, the pass device is off and the output voltage will be zero. The typical standby current is 0.18 mA. Error Amplifier/Output Voltage Program A fully compensated error amplifier is provided inside the NCP1500. No external circuitry is required to stabilize the operation of the NCP1500. The error amplifier provides an error signal to both the PWM circuit and the linear regulator circuit. The output of the error amplifier is directly connected to the linear regulator control circuit. However, the output of the error amplifier is connected first to a subtraction circuit before going to the input of the PWM comparator. The subtraction circuit is activated only during an over current condition. During this condition, a signal proportional to the amount of over current is subtracted from the error amplifier signal. This subtraction results in a lower signal applied to the PWM comparator, thus lowering the output duty cycle. The output voltage is digitally programmable up to four voltages. Two program pins are provided to accomplish this task. The program pins control a mux, which switch a bank of resistors. The appropriate resistor bank is switched to the error amplifier input, depending on the program input. The following truth table can be used to program the output voltage:
CB0 0 0 CB1 0 1 0 1 Output Voltage 1.5 1.8 1.3 1.0
The NCP1500 has a SYNC input. The device operates at a fixed switch frequency determined by the frequency of the synchronization signal applied. The part automatically operates in PWM mode after synchronization pulses are present for several cycles. The NCP1500 will output 2 pulses when a sync signal is present. The first is a PWM pulse. This pulse `sets' a latch that initiates output switch conduction. The width of this pulse controls the minimum on time in PWM mode. The second signal is a slope compensation ramp. A ramp signal is generated. This signal is summed with the current information before being fed into the PWM comparator. The purpose of this circuit is to provide stable operation at output switch duty cycles in excess of 50%. The device automatically switches to linear mode when the SYNC signal is removed for approximately 6.0 msec. It is recommended that the sync signal be externally pulled low to enable the linear mode. Pulling the pin high or open may cause portions of the circuit to remain active, increasing the total current consumption of the IC. The threshold level of the SYNC signal is typically 1.3 V. The duty cycle of the sync signal must be within 20 to 80%.
Internal CLK Signal VIN
1 1
0 External SYNC Signal 3.0
Both program pins are internally pulled low. Thus, if the input pins are left open, the output voltage will be 1.5 V.
0
0
TIME (m)
10
Figure 3. Timing Diagram of the SYNC Signal
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NCP1500
PWM Section The PWM section consists of a PWM comparator, set dominant latch, slope compensation circuit, current sense circuit, and current limit circuit. The NCP1500 operates as a current mode regulator in PWM mode. In this mode, a PWM pulse from the synchronization section initiates the output switch conduction. Output switch conduction is terminated when the peak inductor current reaches a threshold level established by the error amplifier. The output switch conduction duty cycle is allowed to go to 100% to increase transient load response when going from light load to heavy load. A reset dominant latch is provided in the NCP1500. A 3 input OR gate controls the reset pin. Any one of the 3 inputs will terminate output switch conduction. Once terminated, output switch conduction cannot begin again until the next PWM pulse. The only state the NCP1500 does not switch every cycle is if the 5% overvoltage comparator trips. When the comparator trips, the switching regulator will remain off until the voltage drops below the nominal voltage. This state is similar to a PFM mode of operation. Output switch conduction can begin at the next PWM cycle after the OVP input is reset. Current mode controllers can exhibit an instability at duty cycles over 50%. A slope compensation circuit is provided inside the NCP1500 to overcome the potential instability. Slope compensation consists of a ramp signal generated by the synchronization block and adding this to the current signal. The summed signal is then applied to the PWM comparator. A current limit feature is provided in the PWM mode only. The current limit is set to allow peak switch current in excess of 800 mA. It is implemented as a cycle-by-cycle current limit. Each on-cycle is treated as a separate situation. Current limiting is implemented by monitoring the output switch transistor current buildup during conduction. An error signal is generated upon sensing an over-current condition. This signal is subtracted from the error amplifier output. This in turn reduces the PWM comparison threshold voltage, thus limiting the output duty cycle.
3.6040 3.6000 3.5960 400 m 200 m 0.00 400 m 300 m 200 m 400 m 100 m -200 m 1.01 1.00 990 m 3.70 1.35 -1.00 198.0
VIN
IFET
IL
Idiode
VO
VLX
201.0
204.0 TIME (m)
207.0
210.0
213.0
Figure 4. PWM Waveforms During Normal Operation
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NCP1500
Linear Mode Operation The NCP1500 operates as a linear regulator if the synchronization signal is absent. The part is designed to provide up to 50 mA nominally in this mode. Transients of up to 100 mA can be accommodated if the thermal impact is low. The main output is in series with an external inductor. This can cause a lag in the transient response of the device when going from light load to heavy load. A bypass transistor is incorporated to release the energy stored in the inductor in order to avoid oscillation within the operation range. (Patent Pending). The following figure shows the transient step load response of the NCP1500 in this mode of operation.
IOUT (mA)
10
1.0 0 500 1000 1500
DVOUT (mV)
20 0 -20 0 500 Time (ms) 1000 1500
VIN = 3.6 V VOUT = 1.8 V CIN = 10 mF COUT = 10 mF
Figure 5. Load Transient Response in Linear Mode
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NCP1500
Over Voltage Protection NCP1500 has an overvoltage protection circuit that protects the output during the PWM mode. Normally, in PWM mode, the output switch will conduct at the onset of every synchronization pulse. The minimum output duty cycle is 3%. The output voltage will rise at minimum duty cycle and a light load or no load condition is present at the output. If the output rises more than 5% of the programmed voltage, an overvoltage comparator will trip. This signal will reset the PWM latch and hold it in a reset condition until the output voltage decays below its threshold. The output will then be allowed to switch at the next synchronization pulse. This type of operation is usually referred to as PFM or skip mode operation. The following figure is a simulation of the regulator during this condition:
Note: PP - Patent Pending VIN 3.6040 3.6000 3.5960 Main FET Current 250.0 m 124.5 m -1.000 m 20 m 10 m 0.0 -10 m 150 m 25.0 m -100 m 4.00 1.75 -500 m 1.05150 1.05080 1.05010 Gate Voltage for Switching FET 4.0 2.0 0.0 175.00000 181.33333 187.66667 194.00000 TIME (m) 200.33333 206.66667 213.00000 VO (Set to 1 V) VLX Diode Current Inductor Current (Fsync = 300 kHz)
Figure 6. Waveforms of PFM Mode Operation During Over Voltage
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NCP1500
Thermal Shutdown Internal Thermal Shutdown circuitry is provided to protect the integrated circuit in the event at the maximum junction temperature is exceeded. When activated, typically at 150C, the PWM latch is reset and the linear regulator control circuitry is disabled. The thermal shutdown circuit is designed with 25C of hysteresis. This means that the PWM latch and the regulator control circuitry cannot be re-enabled until the die temperature drops by this amount. This feature is provided to prevent catastrophic failures from accidental device overheating. It is not intended as a substitute for proper heatsinking. The NCP1500 is contained in the Micro8 package.
VIN
SHD 1.8 V 1.3 V VO 1.0 V
1.5 V
CB0
CB1
Figure 7. Power-Up and Power-Down Sequence
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NCP1500
APPLICATIONS INFORMATION
80 70 60 EFFICIENCY (%) VOUT (V) 50 40 30 20 10 0 2.5 2.7 2.9 3.1 3.3 3.5 VO = 1.5 V VO = 1.3 V VO = 1.0 V VO = 1.8 V 1.77 1.76 1.75 1.74 1.73 1.72 1.71 1.70 1.69 1.68 0 100 200 IOUT, (mA) 300 400 CB0 = Low CB1 = High VIN = 3.6 V
VIN, INPUT VOLTAGE (V)
Figure 8. Efficiency in Linear Mode Operation vs. Input Voltage (IOUT = 10 mA)
90 85 1.8 EFFICIENCY (%) VIN = 3.6 V CIN = 10 mF COUT = 10 mF L = 15 mH PW Load = 8 msec, 3% 1.7 80 75 70 65 60 55 50 45 0 500 1000 IOUT, (mA) 1500 40
Figure 9. Output Voltage vs. Output Current in LDO Mode
VOUT = 1.8 V
VOUT = 1.5 V
VOUT (V)
VIN = 3.6 V CIN = 10 mH COUT = 10 mH L = 15 mH 0 50 100 150 IOUT, (mA) 200 250 300
Figure 10. Output Voltage vs. Output Current in PWM Mode
Figure 11. PWM Efficiency
Table 1. Efficiency Measurement in PWM Mode
VOUT (V) VIN (V) 2.5 3.0 1.5 15 3.6 4.2 2.5 3.0 1.8 18 3.6 4.2 NOTE: IOUT (mA) 1 44% 44% 49% 51% 48% 41% 45% 52% 5 75% 68% 62% 64% 79% 73% 64% 63% 10 82% 76% 71% 66% 86% 80% 76% 71% 20 86% 82% 79% 75% 90% 85% 83% 78% 30 87% 84% 80% 77% 90% 88% 84% 81% 40 88% 85% 83% 80% 91% 88% 86% 83% 60 88% 86% 83% 81% 91% 89% 86% 84% 80 88% 86% 84% 82% 91% 89% 87% 85% 100 90% 86% 84% 82% 91% 89% 87% 85% 200 84% 83% 82% 82% 87% 86% 85% 85% 300 80% 80% 80% 79% 84% 84% 84% 83%
See figure 1 for circuit configuration. Cin = Cout = C3216X5R106M L = D01606T-153
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NCP1500
PACKAGE DIMENSIONS
Micro8 (MSOP-8) 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*
1.04 8X 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
Micro8E
*For additional information on our Pb-Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D.
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NCP1500
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
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NCP1500/D

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