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
■ <1μA Shutdown Current, Quiescent
Current of 300 μA
■ Over-temperature protected
■ Pin Compatible to LTC3406B
■ Offered in Low Profile TSOT-23
package
VFB
VIN
5
4
VOUT
VIN
5
4
SP6659
SP6659
5 Pin TSOT-23
5 Pin TSOT-23
1
RUN
1
2
3
GND
SW
RUN
Adjustable
2
3
GND
SW
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
®
®
2.2μH
2.2μH
V IN
3
4
SW
Cf
SP6659
4.7μF
Ceramic
RUN
V OUT
V IN
4
SP6659
3 SW
V OUT
100pF
R1
1
5
4.7μF
10μF
Ceramic Ceramic
V FB
RUN 1
5
V OUT
10μF
Ceramic
2
2
R2
GND
GND
Adjustable
Date: 9/25/06 Rev C
Fixed
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
1
© 2006 Sipex Corporation
ABSOLUTE MAXIMUM RATINGS
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 ................................................. -40°C to +85°C
Storage Temperature ................................................. -65°C to +150 °C
Junction Temperature (Note 1) .................................................. 125 °C
Lead Temperature (Soldering, 10 sec) ....................................... 300 °C
___________________________ THERMAL
RESISTANCE
Thermal Resistance is specified with approximately 1 square inch of 1 ounce copper.
O JA ................................................................207.4°C/W
O JC ...............................................................110°C/W
ELECTRICAL CHARACTERISTICS
V IN = VRUN = 3.6V, Io = 0mA, T AMB = -40ºC to +85ºC, typical values at 25ºC unless otherwise noted.
The ♦ denotes the specifications which apply over the full operating temperature range, unless otherwise specified.
PARAMETER
Input Voltage Range
MIN
TYP
2.5
MAX
UNITS
5.5
V
CONDITIONS
♦
Input DC Supply Current
Active Mode
300
400
µA
Shutdown Mode
0.1
1
µA
0.6000
0.6120
0.5880
VFB (Feedback Voltage)
V FB = 0.5V, VIN = VRUN
VIN = 3.6V, VRUN = 0.0V
TA = +25ºC
0.5865
0.6000
0.6135
0.5820
0.6000
0.6180
VFB Input Bias Current
85
300
nA
VFB Line Regulation
0.4
1
%/V
♦
V IN = 2.5V to 5.5V
VFB Load Regulation
0.01
%/mA
♦
ILOAD = 0mA to 600mA
Regulated Output Voltage
V
0ºC < T A < +85ºC
♦
-40ºC < TA < +85ºC
V FB = 1.0V
1.455
1.500
1.545
V
♦
SP6659EK1-1.5, -40ºC < T A < +85ºC
1.746
1.800
1.854
V
♦
SP6659EK1-1.8, -40ºC < T A < +85ºC
Minimum Output Voltage
0.6
V
Peak inductor current
0.7
1.0
1.2
A
Oscillator frequency
0.8
1.4
1.8
MHz
P-channel ON resistance
0.4
0.6
Ω
ISW = 100mA
N-channel ON resistance
0.4
0.6
Ω
ISW = -100mA
±0.01
±1.0
µA
1
1.3
V
♦
±0.01
±1.5
µA
♦
V FB = 0.5V, VIN = 2.5V
♦
Closed Loop, ILOAD = 100mA
VIN = 3.6V, VRUN = 0.0V,
SW Leakage Current
Run Threshold Voltage
0.2
Run Leakage Current
Vsw = 0.0V, Vsw = VIN
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 220°C/W
PIN DESCRIPTION
PIN #
PIN NAME
DESCRIPTION
1
RUN
Power down control pin. Forcing this pin above 1.5V enables the device. Forcing this
pin below 0.3V shuts down the device.
2
GND
Ground pin.
3
SW
Switching node.
4
V IN
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
2
© 2006 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
Refer to the typical application schematic, VOUT = 1.8V, TAMB= +27°C
20μS/div
20μS/div
Figure 1: Load Transient 0mA to 600mA
Figure 2: Load Transient 50mA to 600mA
CH 1: Output Voltage, 200mV per division AC-Coupled
CH 3: Inductor Current, 500mA/ div
CH 4: Load Current, 500mA/ div
CH 1: Output Voltage, 100mV per division AC-Coupled
CH 3: Inductor Current, 500mA/ div
CH 4: Load Current, 500mA/ div
20μS/div
20μS/div
Figure 3: Load Transient 100mA to 600mA
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
CH 1: Output Voltage, 100mV per division AC-Coupled
CH 3: Inductor Current, 500mA/ div
CH 4: Load Current, 500mA/ div
1μS/div
40μS/div
Figure 5: Discontinuous Mode
Figure 6: Startup from Shutdown
CH 1: Output Voltage, 10mV per division AC-Coupled
CH 2: SW 2V/div
CH 3: Inductor Current, 500mA/ div
Date: 9/25/06 Rev C
CH 1: RUN pin 2V/div.
CH 2: Vout 1V/div
CH 3: Inductor Current, 500mA/ div
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
3
© 2006 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
Refer to the typical application schematic, VOUT = 1.8V, TAMB= +27°C
1.8Vout Efficiency Vs Output
100
1.8Vout Load Regulation
1.830
Vin=4.2V
90
Vin=3.3V
Vin=2.7V
80
Vout (V)
Efficiency (%)
1.820
70
1.810
60
Vin=2.7V
1.800
Vin=3.3V
50
Vin=4.2 V
1.790
40
1
10
100
0
1000
100
200
1.8Vout Efficiency vs Input voltage
90
600
700
Vin=3.3V
1.830
1.820
1.810
1.800
1.790
1.780
1.770
1.760
85
80
Vout
(V)
Efficiency (%)
500
Output Voltage vs Load Current
1.850
1.840
95
75
70
65
Iout=600mA
60
Iout=100mA
55
Iout=10mA
50
1.750
2
3
4
5
6
0
200
400
600
800
Load Current (mA)
Input Voltage (V)
Figure 9: 1.8Vout Efficiency vs. Input Voltage
1200
Oscillator Frequency vs Supply Voltage
Oscillator Frequency (MHz)
1.6
380
360
340
320
300
280
260
Vo=1.8V
Iload=0A
240
1000
Figure 10: Output Voltage vs. Load Current
Supply Current vs Supply Voltage
400
Supply Current (uA)
400
Figure 8: Load Regulation Vout =1.8V
Figure 7: Efficiency Vs. Load Current, Vout =1.8V
100
300
Output Current (mA)
Output Current (mA)
220
1.5
1.4
Vo=1.8V
Iload=600mA
1.3
1.2
200
2
3
4
5
2
6
4
5
6
Figure 12: Oscillator Frequency vs. Supply Voltage
Figure 11: Supply Current vs. Supply Voltage
Date: 9/25/06 Rev C
3
Input Voltage (V)
Input Voltage (V)
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
4
© 2006 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
Refer to the typical application schematic, VOUT = 1.8V, TAMB= +27°C
2.5Vout Efficiency Vs Output Current
100
2.5Vout Load Regulation
2.520
Vin=4.2V
90
Vin=3.3V
80
Vout (V)
Efficiency (%)
2.510
70
60
Vin=2.7V
Vin=2.7V
2.500
2.490
Vin=3.3V
50
Vin=4.2V
2.480
40
1
10
100
0
1000
100
200
Output Current (mA)
Figure 13: Efficiency Vs. Load Current, Vout =2.5V
600
700
Figure 14: Load Regulation Vout =2.5V
1.5Vout Efficiency Vs Output Current
100
300
400
500
Output Current (mA)
1.5Vout Load Regulation
1.520
Vin=4.2V
Vin=3.3V
1.510
80
Vout (V)
Efficiency (%)
90
70
60
Vin=2.7V
Vin=2.7V
1.500
1.490
Vin=3.3V
50
Vin=4.2V
1.480
40
1
10
100
0
1000
100
200
Figure 15: Efficiency Vs. Load Current, Vout =1.5V
400
500
700
1.2Vout Load Regulation
1.230
Vin=4.2V
Vin=3.3V
90
1.220
80
Vout (V)
Efficiency (%)
600
Figure 16: Load Regulation Vout =1.5V
1.2Vout Efficiency Vs Output Current
100
300
Output Current (mA)
Output Current (mA)
70
60
Vin=2.7V
Vin=2.7V
1.210
1.200
Vin=3.3V
50
Vin=4.2V
1.190
40
1
10
100
1000
0
100
300
400
500
600
Output Current (mA)
Output Current (mA)
Figure 17: Efficiency Vs. Load Current, Vout =1.2V
Date: 9/25/06 Rev C
200
Figure 18: Load Regulation Vout =1.2V
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
5
© 2006 Sipex Corporation
700
FUNCTIONAL DIAGRAMS
SLOPE
COMP
OSC
VIN
2.7 - 5.5V
4
+
CIN
+
BLANKING
-
ISENSE
COMP
R
-
VOUT
0.6V
+
EA
-
5
_
S
_
R
Q
_
Q
RS LATCH
PWM
LOGIC
R1
0.65V
DRV
+
OV
DET
-
R2
SW
NONOVERLAP
CONTROL
+
COMP
-
COUT
+
Izero
COMP
-
VIN
RUN
2
GND
0.6V
REF
1
VOUT
3
SHUTDOWN
Fixed Output Version
SLOPE
COMP
OSC
4
+
BLANKING
+
-
CIN
ISENSE
COMP
VIN
2.7 - 5.5V
R
-
VFB
0.6V
0.65V
+
COMP
-
Q
_
Q
RS LATCH
+
OV
DET
-
PWM
LOGIC
DRV
+
Izero
COMP
-
VIN
RUN
REF
1
NONOVERLAP
CONTROL
5
+
EA
-
_
S
_
R
SW
VOUT
3
Cf
R1
COUT
R2
2
GND
0.6V
SHUTDOWN
Adjustable Output Version
Date: 9/25/06 Rev C
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
6
© 2006 Sipex Corporation
APPLICATION INFORMATION
_____________________ SETTING THE
OUTPUT VOLTAGE
V OUT
®
R1
A resistive divider based on the following
equation determines the output voltage:
VOUT = 0.6 (1+
SP6659
V FB
R2
R1
)
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.
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
__________________ CURRENT MODE
PWM CONTROL
At very light loads, the SP6659 automatically enters Idle Mode (Figure 21).
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
Date: 9/25/06 Rev C
Figure 21. SP6659 Idle Mode Operation
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
7
© 2006 Sipex Corporation
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.
________________________ 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.
_______________________ 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%.
_______________________ INDUCTOR
SELECTION
For most designs, the SP6659 operates with
inductors of 1μH to 4.7μH. 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:
The duty cycle D of a step-down converter is
defined as:
D = TON X
ƒOSC
X 100%
≈ VOUT
X 100%
VIN
L = VOUT X (VINMax - VOUT)
VINMax X ΔIL X ƒOSC
where TON is the main switch on time, and
ƒOSC is the oscillator frequency (1.5Mhz).
Where ΔIL 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.
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.
Date: 9/25/06 Rev C
For output voltages above 2.0V, when lightload efficiency is important, the minimum
recommended inductor is 2.2μH. For optimum voltage-positioning load transients,
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
8
© 2006 Sipex Corporation
THEORY OF OPERATION
________________ INPUT CAPACITOR
SELECTION
choose an inductor with DC series resistance in the 50mΩ to 150mΩ range. For
higher efficiency at heavy loads (above
200mA), or minimal load regulation (but
some transient overshoot), the resistance
should be kept below 100mΩ. 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).
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 4.7μF ceramic capacitor for most
applications is sufficient.
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
(µH)
(mΩ)
Current
(Amps)
Murata
LQH32CN2R2M11
1.0
78
1
3.2x2.5x1.55
Murata
LQH32CN2R2M11
2.2
126
0.79
3.2x2.5x1.55
Murata
LQH32CN4R7M11
4.7
195
0.6 5
3.2x2.5x1.55
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
2.52
1.5
1.44
1.15
4.5x4.0x3.5
75
110
162
120
140
180
240
1.32
1.04
0.84
1.29
1.14
0.98
0.79
Sumida CR43
Sumida CDRH4D18
Toko D312C
______________ OUTPUT CAPACITOR
SELECTION
Size WxLxH
(mm)
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 ΔVOUT is determined by:
4.7x4.7x2.0
ΔVOUT ≤
3.6x3.6x1.2
Inductor in Bold is used on the SP6659EB evaluation Board
VOUT X (VINMax - VOUT)
VINMax X L X ƒOSC
+
X ESR
{
1
(8X ƒOSC X COUT)
Table 1: Typical Surface Mount Inductors
Date: 9/25/06 Rev C
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
9
© 2006 Sipex Corporation
}
PACKAGE: 5 PIN TSOT23
D
D/2
e1
5
SIDE VIEW
4
E/2
E1/2
A2
A
E
E1
Seating
Plane
A1
2
1
Pin1 Designator
to be within this
INDEX AREA
(D/2 x E1/2)
3
(L1)
e
b
TOP VIEW
ø1
FRONT VIEW
R1
R
Gauge Plane
L2
ø
L
5 Pin TSOT-23
SYMBOL
A
A1
A2
c
D
E
E1
L
L1
L2
Ø
Ø1
R
R1
MIN
0.00
0.70
0.08
0.30
0˚
4˚
0.10
0.10
0.30
ø1
JEDEC MO-193
Dimensions in Millimeters:
Controlling Dimension
b
e
e1
SIPEX Pkg Signoff
Date: 9/25/06 Rev C
Seating
Plane
NOM
0.90
2.90 BSC
2.80 BSC
1.60 BSC
0.45
0.60 REF
0.25 BSC
4º
10º
0.95 BSC
1.90 BSC
Date/Rev:
MAX
1.10
0.10
1.00
0.20
0.60
8º
12º
0.25
0.50
c
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
0º
4º
8º
4º
10º
12º
0.004
0.004
0.010
0.012
0.020
0.038 BSC
0.075 BSC
JL Aug4-05 / Rev A
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
10
© 2006 Sipex Corporation
ORDERING INFORMATION
Part Number
Operating Temperature Range
Package Type
SP6659EK1 ......... ...............................-40°C to +85°C ........................................................... 5 Pin TSOT23
SP6659EK1/TR .... ...............................-40°C to +85°C ........................................................... 5 Pin TSOT23
SP6659EK1-1-5 .... ...............................-40°C to +85°C ........................................................... 5 Pin TSOT23
SP6659EK1-1-5/TR...............................-40°C to +85°C .......................................................... 5 Pin TSOT23
SP6659EK1-1-8 .... ...............................-40°C to +85°C ........................................................... 5 Pin TSOT23
SP6659EK1-1-8/TR...............................-40°C to +85°C .......................................................... 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
11
© 2006 Sipex Corporation