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SP6659
1.5MHz, 600mA Synchronous Buck Regulator
FEATURES 94% Efficiency Possible 600mA Output Current at VIN = 3.6V 2.5V to 5.5V Input Voltage Range 1.5MHz constant frequency operation No Schottky Diode Required Output Voltages as low as 0.6V Slope Compensated Current Mode Operation for Excellent Line and Load Transient Response 100 % Duty Cycle in LDO Mode <1A Shutdown Current, Quiescent Current of 300 A Over-temperature protected Pin Compatible to LTC3406B Offered in Low Profile TSOT-23 package
VFB
VIN
VOUT
VIN
5
4
5
4
SP6659
5 Pin TSOT-23
1
RUN
SP6659
5 Pin TSOT-23
1
RUN
2
GND
3
SW
2
GND
3
SW
Adjustable
Fixed
Now Available in Lead Free Packaging APPLICATIONS Cell Phones Wireless and DSL Modems DSC's Portable Instruments DESCRIPTION
The SP6659 is a 600mA synchronous buck regulator using a constant frequency, current mode architecture. The output voltage can be programmed using an external resistor divider. The 2.5V to 5.5V input voltage range is ideal for portable applications that use a Li-Ion battery. Switching frequency is internally set at 1.5MHz, allowing the use of small surface mount inductors and capacitors. The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. The output voltage can be programmed using an external resistor divider. Low output voltages are easily supported with the 0.6V feedback reference voltage. The SP6659 is available in a low profile 5 pin TSOT-23 package. TYPICAL APPLICATION SCHEMATICS
(R)
(R)
2.2H V IN RUN
4 3
2.2H
Cf
SW
100pF
V OUT
V IN
4
SP6659
3 SW
V OUT
SP6659
R1
1 5 2
4.7F Ceramic
V FB R2
4.7F 10F Ceramic Ceramic
RUN 1
5 2
V OUT
10F Ceramic
GND
GND
Adjustable
Fixed
Date: 9/25/06 Rev C
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
(c) 2006 Sipex Corporation
1
These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. Input Supply Voltage ......................................................... -0.3V to +6V RUN, VFBVoltages .................................................. -0.3V to (VIN + 0.3V) SW Voltage ............................................................ -0.3V to (VIN + 0.3V) P-Channel Switch Source Current (DC) ..................................... 800mA N-Channel Switch Sink Current (DC) ......................................... 800mA Peak Switch Sink and Source Current ........................................... 1.3A Operating Temperature ................................................. -40C to +85C Storage Temperature ................................................. -65C to +150 C Junction Temperature (Note 1) .................................................. 125 C Lead Temperature (Soldering, 10 sec) ....................................... 300 C
ABSOLUTE MAXIMUM RATINGS
___________________________ THERMAL
RESISTANCE
Thermal Resistance is specified with approximately 1 square inch of 1 ounce copper.
O JA ................................................................207.4C/W O JC ...............................................................110C/W
ELECTRICAL CHARACTERISTICS
VIN = VRUN = 3.6V, Io = 0mA, T AMB = -40C to +85C, typical values at 25C unless otherwise noted. The denotes the specifications which apply over the full operating temperature range, unless otherwise specified.
PARAMETER
Input Voltage Range Input DC Supply Current Active Mode Shutdown Mode
MIN
2.5
TYP
MAX
5.5
UNITS
V
CONDITIONS
300 0.1 0.5880 0.6000 0.6000 0.6000 85 0.4 0.01 1.455 1.746 0.6 0.7 0.8 1.0 1.4 0.4 0.4 0.01 0.2 1 0.01 1.500 1.800
400 1 0.6120 0.6135 0.6180 300 1
A A
VFB = 0.5V, VIN = VRUN VIN = 3.6V, VRUN = 0.0V TA = +25C
VFB (Feedback Voltage)
0.5865 0.5820
V nA %/V %/mA
0C < TA < +85C -40C < TA < +85C VFB = 1.0V VIN = 2.5V to 5.5V ILOAD = 0mA to 600mA SP6659EK1-1.5, -40C < TA < +85C SP6659EK1-1.8, -40C < TA < +85C
VFB Input Bias Current VFB Line Regulation VFB Load Regulation Regulated Output Voltage Minimum Output Voltage Peak inductor current Oscillator frequency P-channel ON resistance N-channel ON resistance SW Leakage Current
1.545 1.854
V V V
1.2 1.8 0.6 0.6 1.0 1.3 1.5
A MHz A V
VFB = 0.5V, VIN = 2.5V Closed Loop, ILOAD = 100mA ISW = 100mA ISW = -100mA VIN = 3.6V, VRUN = 0.0V, Vsw = 0.0V, Vsw = VIN
Run Threshold Voltage Run Leakage Current
A
Note 1: Junction Temperature TJ is calculated from the ambient temperature TA and ower dissipation PD according to the following formula: TJ = TA + PD X 220C/W
PIN DESCRIPTION
PIN # 1 2 3 4
PIN NAME RUN GND SW V IN
DESCRIPTION Power down control pin. Forcing this pin above 1.5V enables the device. Forcing this pin below 0.3V shuts down the device. Ground pin. Switching node. Power supply pin Adjustable Version: VFB, Feedback Input Pin. Connect FB to the center point of the external resistor divider. The feedback threshold voltage is 0.6V.
5
VFB / VOUT Fixed Output Version: VOUT, Output Voltage Feedback Pin. An internal resistive divider drops the output voltage down for comparison to the internal reference voltage.
Date: 9/25/06 Rev C
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
(c) 2006 Sipex Corporation
2
TYPICAL PERFORMANCE CHARACTERISTICS Refer to the typical application schematic, VOUT = 1.8V, TAMB= +27C
20S/div
20S/div
Figure 1: Load Transient 0mA to 600mA
CH 1: Output Voltage, 200mV per division AC-Coupled CH 3: Inductor Current, 500mA/ div CH 4: Load Current, 500mA/ div
Figure 2: Load Transient 50mA to 600mA
CH 1: Output Voltage, 100mV per division AC-Coupled CH 3: Inductor Current, 500mA/ div CH 4: Load Current, 500mA/ div
20S/div
20S/div
Figure 3: Load Transient 100mA to 600mA
CH 1: Output Voltage, 100mV per division AC-Coupled CH 3: Inductor Current, 500mA/ div CH 4: Load Current, 500mA/ div
Figure 4: Load Transient 200mA to 600mA
CH 1: Output Voltage, 100mV per division AC-Coupled CH 3: Inductor Current, 500mA/ div CH 4: Load Current, 500mA/ div
1S/div
Figure 5: Discontinuous Mode
CH 1: Output Voltage, 10mV per division AC-Coupled CH 2: SW 2V/div CH 3: Inductor Current, 500mA/ div
40S/div
Figure 6: Startup from Shutdown
CH 1: RUN pin 2V/div. CH 2: Vout 1V/div CH 3: Inductor Current, 500mA/ div
Date: 9/25/06 Rev C
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
(c) 2006 Sipex Corporation
3
TYPICAL PERFORMANCE CHARACTERISTICS Refer to the typical application schematic, VOUT = 1.8V, TAMB= +27C
100 90
1.8Vout Efficiency Vs Output
1.830
1.8Vout Load Regulation
Vin=4.2V Vin=3.3V
1.820
Efficiency (%)
80
Vout (V)
Vin=2.7V
70 60
Vin=2.7V
1.810
1.800
50 40 1 10 100
Vin=3.3V Vin=4.2 V
1.790
1000
0
100
200
300
400
500
600
700
Output Current (mA)
Output Current (mA)
Figure 7: Efficiency Vs. Load Current, Vout =1.8V
Figure 8: Load Regulation Vout =1.8V
100 95 90
Efficiency (%)
1.8Vout Efficiency vs Input voltage
1.850 1.840 1.830 1.820 1.810 1.800 1.790 1.780 1.770 1.760 1.750
2 3 4 5 6
Output Voltage vs Load Current
Vin=3.3V
85 80 75 70 65 60 55 50 Iout=600mA Iout=100mA Iout=10mA
Vout (V)
0
200
Input Voltage (V)
400 600 800 Load Current (mA)
1000
1200
Figure 9: 1.8Vout Efficiency vs. Input Voltage
Figure 10: Output Voltage vs. Load Current
400 380
Supply Current (uA)
Supply Current vs Supply Voltage
Oscillator Frequency (MHz)
1.6
Oscillator Frequency vs Supply Voltage
360 340 320 300 280 260 240 220 200 2 3 4 5 6
1.5
1.4
Vo=1.8V Iload=600mA
Vo=1.8V Iload=0A
1.3
1.2
2 3 4 5 6
Input Voltage (V)
Input Voltage (V)
Figure 11: Supply Current vs. Supply Voltage
Figure 12: Oscillator Frequency vs. Supply Voltage
Date: 9/25/06 Rev C
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
(c) 2006 Sipex Corporation
4
TYPICAL PERFORMANCE CHARACTERISTICS Refer to the typical application schematic, VOUT = 1.8V, TAMB= +27C
100 90
2.5Vout Efficiency Vs Output Current
2.520
2.5Vout Load Regulation
Vin=4.2V Vin=3.3V
2.510
Efficiency (%)
Vout (V)
Vin=2.7V
80 70 60 50 40 1 10 100 1000
Vin=2.7V Vin=3.3V Vin=4.2V
2.500
2.490
2.480 0 100 200 300 400 500 Output Current (mA) 600 700
Output Current (mA)
Figure 13: Efficiency Vs. Load Current, Vout =2.5V
Figure 14: Load Regulation Vout =2.5V
100 90
Efficiency (%)
1.5Vout Efficiency Vs Output Current
1.520
1.5Vout Load Regulation
Vin=4.2V Vin=3.3V Vin=2.7V
1.510
Vout (V)
80 70 60 50 40 1 10 100 1000
Vin=2.7V Vin=3.3V Vin=4.2V
1.500
1.490
1.480 0 100 200 300 400 500 600 700
Output Current (mA)
Output Current (mA)
Figure 15: Efficiency Vs. Load Current, Vout =1.5V
Figure 16: Load Regulation Vout =1.5V
100 90
1.2Vout Efficiency Vs Output Current
1.230
1.2Vout Load Regulation
Vin=4.2V Vin=3.3V
1.220
Efficiency (%)
Vout (V)
Vin=2.7V
80 70 60 50 40 1 10 100 1000
Vin=2.7V Vin=3.3V Vin=4.2V
1.210
1.200
1.190 0 100 200 300 400 500 600 700
Output Current (mA)
Output Current (mA)
Figure 17: Efficiency Vs. Load Current, Vout =1.2V
Figure 18: Load Regulation Vout =1.2V
Date: 9/25/06 Rev C
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
(c) 2006 Sipex Corporation
5
FUNCTIONAL DIAGRAMS
OSC
SLOPE COMP
4 CIN
+ -
VIN 2.7 - 5.5V
BLANKING
+
ISENSE COMP R
-
VOUT
5 R1
0.6V
+ EA -
+ COMP -
Q _ Q RS LATCH PWM LOGIC DRV
_ S _ R
SW
3
NONOVERLAP CONTROL
VOUT
0.65V
+ OV DET + Izero COMP 0.6V
R2
VIN
COUT
2
RUN
1 REF
GND
SHUTDOWN
Fixed Output Version
OSC
SLOPE COMP
4
BLANKING
ISENSE COMP
+
R
CIN
+ -
VIN 2.7 - 5.5V
-
VFB
5
0.6V
+ EA -
+ COMP + OV DET -
Q _ Q RS LATCH
_ S _ R
PWM LOGIC
SW
3 R1 COUT R2 2
NONOVERLAP CONTROL
DRV
VOUT
Cf
0.65V VIN
RUN
1 REF
+ Izero COMP 0.6V SHUTDOWN
GND
Adjustable Output Version
Date: 9/25/06 Rev C
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
(c) 2006 Sipex Corporation
6
APPLICATION INFORMATION _____________________ SETTING THE OUTPUT VOLTAGE
(R)
V OUT R1
A resistive divider based on the following equation determines the output voltage: VOUT = 0.6 (1+ R1 ) R2
SP6659
V FB
R2 GND
The external resistive divider is connected to the output as shown in Figure 20 .
Figure 20: Setting the SP6659 Output Voltage.
THEORY OF OPERATION The SP6659 is a monolithic switching mode Step-Down DC-DC converter. It utilizes internal MOSFETs to achieve high efficiency and can generate very low output voltage by using its internal reference at 0.6V. It operates at a fixed switching frequency, and uses slope compensated, current-mode architecture. This Step-Down DC-DC converter supplies 600mA of output current at VIN = 3V. The entire input voltage range is from 2.5V to 5.5V. __________________ CURRENT MODE PWM CONTROL Slope compensated current mode PWM control provides stable switching and cycleby-cycle current limit for excellent load and line responses and protection of the internal main switch (P-Channel MOSFET) as well as the synchronous rectifier (N-Channel MOSFET). During normal operation, the internal P-Channel MOSFET is turned on for a certain time to ramp the inductor current at each rising edge of the internal oscillator, and switched off when the peak inductor current is above the error voltage. The current comparator, ICOMP, limits the peak inductor current. When the main switch is off, the synchronous rectifier will be turned on immediately and stay on until either the inductor current starts to reverse, as indicated by the current reversal comparator, IZERO, or the beginning of the next clock cycle. The OVDET comparator controls output transient overshoots by turning the main switch off and keeping it off until the fault is no longer present. _______________________ IDLE MODE OPERATION At very light loads, the SP6659 automatically enters Idle Mode (Figure 21).
Figure 21. SP6659 Idle Mode Operation
Date: 9/25/06 Rev C
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
(c) 2006 Sipex Corporation
7
THEORY OF OPERATION In the Idle Mode, the inductor current may reach zero Amps or reverse on each pulse. The PWM control loop will automatically skip pulses to maintain output regulation. The bottom MOSFET is turned off by the current reversal comparator, IZERO, and the switch voltage will ring. This is the discontinuous mode of operation, and is normal behavior for the switching regulator. _______________________ DROPOUT OPERATION When the input voltage decreases toward the value of the output voltage, the SP6659 allows the main switch to remain on for more than one switching cycle and increases the duty cycle until it reaches 100%. The duty cycle D of a step-down converter is defined as:
D = TON X
________________________ MAXIMUM LOAD CURRENT The SP6659 will operate with an input supply voltage as low as 2.5V, however, the maximum load current decreases at lower inputs due to a large IR drop on the main switch and synchronous rectifier. The slope compensation signal reduces the peak inductor current as a function of the duty cycle to prevent sub-harmonic oscillations at duty cycles greater than 50%. Conversely, the current limit increases as the duty cycle decreases. _______________________ INDUCTOR SELECTION For most designs, the SP6659 operates with inductors of 1H to 4.7H. Low inductance values are physically smaller but require faster switching, which can result in some efficiency loss. The inductor value can be derived from the following equation: L = VOUT X (VINMax - VOUT) VINMax X IL X OSC
OSC
X 100%
VOUT X 100% VIN
where TON is the main switch on time, and OSC is the oscillator frequency (1.5Mhz). The output voltage then is the input voltage minus the voltage drop across the main switch and the inductor. At low input supply voltages, the R DSON of the P-Channel MOSFET increases, and the efficiency of the converter decreases. Caution must be exercised to ensure that the heat dissipated does not exceed the maximum junction temperature of the IC.
Where IL is the inductor Ripple Current. Large value inductors lower ripple current and small value inductors result in higher ripple current. Choose inductors at ripple current of approximately 35% of the maximum load current 600mA, or ~ 210mA. For output voltages above 2.0V, when lightload efficiency is important, the minimum recommended inductor is 2.2H. For optimum voltage-positioning load transients,
Date: 9/25/06 Rev C
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
(c) 2006 Sipex Corporation
8
THEORY OF OPERATION ________________ INPUT CAPACITOR SELECTION The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input capacitor impedance at the switching frequency shall be less than input source impedance to prevent high frequency switching current from passing to the input. A low ESR (Equivalent Series Resistance) input capacitor sized for maximum RMS current must be used. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. A 4.7F ceramic capacitor for most applications is sufficient. ______________ OUTPUT CAPACITOR SELECTION The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. The output capacitor must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended due to their low ESR and high ripple current. The output ripple VOUT is determined by:
choose an inductor with DC series resistance in the 50m to 150m range. For higher efficiency at heavy loads (above 200mA), or minimal load regulation (but some transient overshoot), the resistance should be kept below 100m. The DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation (600mA+105mA). Table 1 lists some typical surface mount inductors that meet target applications for the SP6659.
SP6659 Inductor Selection Chart Part # Inductor Max DCR Rated DC (H) (m) Current (Amps) Size WxLxH (mm)
Murata LQH32CN2R2M11 Murata LQH32CN2R2M11
Murata LQH32CN4R7M11
1.0
78
1
3.2x2.5x1.55
2.2
4.7
126
195
0.79
0.6 5
3.2x2.5x1.55
3.2x2.5x1.55
Sumida CR43
Sumida CDRH4D18
Toko D312C
1.4 2.2 3.3 4.7 1.5 2.2 3.3 4.7 1.5 2.2 3.3 4.7
56.2 71.2 86.2 108.7 75 110 162 120 140 180 240
2.52 1.5 1.44 1.15 1.32 1.04 0.84 1.29 1.14 0.98 0.79
4.5x4.0x3.5
4.7x4.7x2.0
3.6x3.6x1.2
VOUT VOUT X (VINMax - VOUT) VINMax X L X OSC
Inductor in Bold is used on the SP6659EB evaluation Board
+ X ESR
{
1 (8X OSC X COUT)
}
Table 1: Typical Surface Mount Inductors
Date: 9/25/06 Rev C
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
(c) 2006 Sipex Corporation
9
PACKAGE: 5 PIN TSOT23
D/2 e1
5
D
4
SIDE VIEW
E/2 E A A1 A2 Seating Plane
E1/2 E1
1
2
3
(L1)
Pin1 Designator to be within this INDEX AREA (D/2 x E1/2)
e
TOP VIEW
b
FRONT VIEW
Gauge Plane L2 o L Seating Plane o1
o1
R1 R
c
5 Pin TSOT-23
SYMBOL
JEDEC MO-193
Variation AB Dimensions in Inches Conversion Factor: 1 Inch = 25.40 mm MIN NOM MAX 0.043 0.000 0.004 0.028 0.036 0.039 0.003 0.008 0.114 BSC 0.110 BSC 0.063 BSC 0.012 0.018 0.024 0.024 REF 0.010 BSC 0 4 8 4 10 12 0.004 0.004 0.010 0.012 0.020 0.038 BSC 0.075 BSC JL Aug4-05 / Rev A
Dimensions in Millimeters: Controlling Dimension MIN 0.00 0.70 0.08 NOM 0.90 2.90 BSC 2.80 BSC 1.60 BSC 0.45 0.60 REF 0.25 BSC 4 10 0.95 BSC 1.90 BSC Date/Rev: MAX 1.10 0.10 1.00 0.20
A A1 A2 c D E E1 L L1 L2 O O1 R R1
0.30
0.60
b e e1 SIPEX Pkg Signoff
0 4 0.10 0.10 0.30
8 12 0.25 0.50
Date: 9/25/06 Rev C
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
(c) 2006 Sipex Corporation
10
ORDERING INFORMATION
Part Number Operating Temperature Range Package Type
SP6659EK1 ......... ...............................-40C to +85C ........................................................... 5 Pin TSOT23 SP6659EK1/TR .... ...............................-40C to +85C ........................................................... 5 Pin TSOT23 SP6659EK1-1-5 .... ...............................-40C to +85C ........................................................... 5 Pin TSOT23 SP6659EK1-1-5/TR...............................-40C to +85C .......................................................... 5 Pin TSOT23 SP6659EK1-1-8 .... ...............................-40C to +85C ........................................................... 5 Pin TSOT23 SP6659EK1-1-8/TR...............................-40C to +85C .......................................................... 5 Pin TSOT23 Available in lead free packaging. To order add "-L" suffix to part number. Example: SP6659EK1/TR = standard; SP6659EK1-L/TR = lead free /TR = Tape and Reel Pack quantity is 2,500 for TSOT23.
Sipex Corporation Headquarters and Sales Office 233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600 Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.
Date: 9/25/06 Rev C
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
(c) 2006 Sipex Corporation
11

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