SP6656
High Efficiency 400mA Synchronous Buck Regulator
with Dynamically Adjustable Voltage Output
FEATURES
■
98% Efficiency Possible
■
Offered in small 2.4 x 2.5mm DFN
■
Ultra-low 20µA Quiescent Current
■
625mA Inductor Peak Current Limit
■
Guaranteed Minimum 400mA Output
Current
■
2.7V to 5.5V Input Voltage Range
■
Output Adjustable Down to 1.0V
■
100% Duty Ratio Low Dropout
Operation
■
80µA Light Load Quiescent Current in
Dropout
■
Dynamic Adjustable Output Voltage
■
Ideal for portable designs powered with
Li Ion battery
P
VIN
VIN
OVSO
OVSI
EN
1
2
3
4
5
10
LX
PGND
GND
V
OUT
SP6656
10 Pin DFN
9
8
7
6
FB
Now Available in Lead Free Packaging
APPLICATIONS
■
Cell Phones
■
PDA's
■
DSC's
■
MP3 Players
■
USB Devices
■
Point of Use Power
DESCRIPTION
The SP6656 is a 400mA synchronous buck regulator that is ideal for portable applications that
use a Li-Ion or 3 cell alkaline/NiCD/NiMH input. The SP6656’s proprietary control loop, 20µA light
load quiescent current, and 0.3Ω power switches provide excellent efficiency across a wide range
of output currents. As the input battery supply decreases towards the output voltage the SP6656
seamlessly transitions into 100% duty ratio operation further extending useful battery life. The
SP6656 is protected against overload and short circuit conditions with a precise inductor peak
current limit. Other features include externally programmable output voltage down to 1.0V,
dynamically adjustable output voltage, logic level shutdown control, and 140°C over temperature
shutdown.
TYPICAL APPLICATION SCHEMATIC
2.7V to 5.5V Input
VI
3.2 x 1.6 x 1.55mm
C
IN
10µF
10Ω
R
VIN
CV
IN
1µF
V
OUT
400mA
VO
SP6656
P
VIN
V
IN
OVSO
OVSI
EN
LX
P
GND
GND
L1
10µH
C
OUT
10µF
CF
R
F
22pF
V
OUT
FB
R
S
R
I
Date: 3/6/06
SP6656, 400mA Synchronous Buck Regulator with Dynamically Adjustable Voltage Output
© Copyright 2006 Sipex Corporation
1
ABSOLUTE MAXIMUM RATINGS
PV
IN
,V
IN
.............................................................................................. 6V
All other pins .............................................................. -0.3V to V
IN
+0.3V
PV
IN
, P
GND
, LX current ........................................................................ 2A
Storage Temperature .................................................. -65
°C
to 150
°C
Operating Temperature ................................................. -40°C to +85°C
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.
ELECTRICAL CHARACTERISTICS
V
IN
= UV
IN
= V
EN
= 3.6V, V
OUT
= V
FB
, I
O
= 0mA, T
AMB
= -40°C to +85°C, typical values at 25°C unless otherwise noted.
PARAMETER
Input Voltage Operating
Range
Minimum Output Voltage
FB Set Voltage, Vr
Overall Accuracy
(-40°C to 85°C)
(0°C to 70°C)
On-Time Constant - K
ON
Min, T
ON
=K
ON
/(V
IN
-V
OUT
)
Off-Time Constant - K
OFF
Min, T
OFF
=K
OFF
/V
OUT
Off-Time Blanking
Turn On Time
PMOS Switch Resistance
NMOS Switch Resistance
Inductor Current Limit
Power Efficiency
Minimum Guaranteed Load
Current
V
IN
Quiescent Current
V
IN
Shutdown Current
V
OUT
Quiescent Current
V
OUT
Shutdown Current
UVLO
Undervoltage Lockout
Threshold, V
IN
falling
UVLO hysteresis
OVSO Output Voltage
OVSO Leakage Current
Over-Temperature
Rising Trip Point
Over-Temperature Hysteresis
EN Leakage Current
EN Input Threshold Voltage
FB Leakage Current
LX Leakage
OVSI Leakage Current
OVSI Input Threshold Voltage
MIN
UVLO
1.0
0.784
TYP
MAX
5.5
UNITS
V
V
V
CONDITIONS
0.800
0.816
1.5
1.6
2.25
2.4
100
250
0.3
0.3
625
96
92
500
20
1
2
1
±5
±4
3.0
3.2
%
V*µs
V*µs
ns
µs
Ω
Ω
mA
%
mA
25°C, I
O
= 200mA Close Loop. L
I
= 10µH,
C
OUT
= 22µF
Measured at V
IN
= 5.5V, no load and
V
IN
=3.6V, 200mA load, Close Loop
Close Loop, L
I
= 10µH,C
OUT
= 22µF
Inductor current limit tripped, VFB = 0.5V
Measured at V
OUT
= 1V
400mA Load
I
PMOS
= 200mA
I
NMOS
= 200mA
VFB = 0.5V
V
OUT
= 2.5V, I
O
= 200mA
V
OUT
= 3.3V, I
O
= 400mA
500
400
0.6
0.6
750
400
30
500
5
500
2.85
µA
nA
µA
nA
V
mV
mV
nA
°C
°C
nA
V
V
nA
µA
nA
V
V
OUT
= 3.3V, V
IN
= 3.6V and V
IN
= 5.5V
EN = 0.0V
V
OUT
= 3.3V
EN = 0.0V
EN = V
IN
,
2.55
2.70
40
50
5
140
14
1
0.90
1.25
1
3
1
0.90
1.25
100
100
V
IN
= EN; Iovso =1mA; OVSI = 1 = Vcc
V
IN
= EN; Vovso= 3.6V;OVSI= 0.0V= GND
500
1.8
100
5
500
1.8
0.60
High to Low Transition
Low to High Transition
FB =1V
EN = 0.0V, V
IN
= 3.6V
LX = 0.0V, LX = V
IN
+ 0.2V
High to Low Transition
Low to High Transition
0.60
Date: 3/6/06
SP6656, 400mA Synchronous Buck Regulator with Dynamically Adjustable Voltage Output
© Copyright 2006 Sipex Corporation
2
PIN DESCRIPTION
PIN NUMBER
1
2
3
4
5
6
PIN NAME
P
VIN
V
IN
OVSO
OVSI
EN
FB
DESCRIPTION
Input voltage power pin. Inductor charging current passes through this pin.
Internal supply voltage. Control circuitry powered from this pin.
Output Voltage Selection Output. OVSI = 1 pulls this node to
GND, OVSI = 0, this node is open.
Output Voltage Select Input. See table 1 for definition.
EN = 1, device is enabled. EN = 0, All internal circuitry is disabled and
power switches are opened.
External feedback network input connection. Connect a resistor from
FB to ground and FB to V
OUT
to set the output voltage. This pin
regulates to the internal bandgap reference voltage of 0.8V.
Output voltage sense pin. Used by the timing circuit to set minimum on
and off times.
Internal ground pin. Control circuitry returns current to this pin.
Power ground pin. Synchronous rectifier current returns through this pin.
Inductor switching node. Inductor tied between this pin and the output
capacitor to create regulated output voltage.
V
OUT
VO
7
8
9
10
V
OUT
GND
P
GND
LX
OVSI
0
1
OVSO
Open
Short to GND
Output Voltage
V
OUT_LOW
= 0.8 (R
I
+R
F
) / R
I
V
OUT_HIGH
= 0.8 (R
A
+R
F
) /R
A
CF
R
F
22pF
FB
R
I
R
S
OVSO
Table 1. Output Voltage Selection
Note:
R
A
= R
I
R
S
R
I
+R
S
FUNCTIONAL DIAGRAM
V
IN
DRVON
VOLOW
T
ONOVER
MIN Ton
Internal Supply
T
ONOVER
Vos
VOLOW
REF
+
-
REF'
+
V
RAMP
Min Ton
Min T
ON
=
K
ON
/(V
IN
-V
OUT
)
M
DRVON
R
S
Q
V
OUT
P
VIN
1
OVR_I
+
DRIVER
-
C
ILIM/M
_
Q
-
C
FB
+
-
FB'
RST
OVR_I
LX
DRVON
REF
Ref
Block
UVLO
TSD
+
One-Shot
=100ns
BLANK
-
C
Zero_X
EN
ILIM/M
P
GND
T
OFF
=
K
OFF
/V
OUT
OVSI
GND
DRVON
BLANK
BLANK = T
BLANK
(=100ns) or T
OFF
= K
OFF
/V
OUT
OVR_I
OVSO
Date: 3/6/06
SP6656, 400mA Synchronous Buck Regulator with Dynamically Adjustable Voltage Output
© Copyright 2006 Sipex Corporation
3
TYPICAL PERFORMANCE CHARACTERISTICS
Refer to the typical application schematic, T
AMB
= +27°C
100
95
Efficiency (%)
Efficiency (%)
100
95
90
85
80
75
70
65
60
0.1
1.0
10.0
ILoad (mA)
100.0
1000.0
Vi=3.6V
Vi=3.9V
Vi=4.2V
Vi=5.0V
90
85
80
75
70
65
60
0.1
1.0
10.0
ILoad (mA)
100.0
1000.0
Vi=3.6V
Vi=3.9V
Vi=4.2V
Vi=5.0V
Efficiency vs. Load, V
OUT
=3.3V
Efficiency vs Load, V
OUT
= 1.5V
3.45
3.40
Vout (V)
1.55
Vi=3.6V
Vi=3.9V
Vi=4.2V
Vi=5.0V
1.53
Vout (V)
3.35
3.30
3.25
3.20
3.15
0
100
200
300
400
500
ILoad (mA)
1.51
1.49
1.47
1.45
0
100
200
300
400
500
ILoad (mA)
Vi=3.6V
Vi=3.9V
Vi=4.2V
Vi=5.0V
Line/Load Rejection, V
OUT
= 3.3V
Line/Load Rejection, V
OUT
= 1.5V
500
Tamb = 85C
Tamb = 25C
Tamb = -40C
50
40
Iin
(
_
A)
400
300
Iin (uA)
30
20
10
0
Tamb = 85C
Tamb = 25C
Tamb = -40C
200
100
0
3.0
3.3
Vin (V)
3.0
3.6
3.9
4.2
3.3
3.6
Vin (V)
3.9
4.2
No Load Battery Current, V
OUT
=3.3V
No Load Battery Current, V
OUT
=1.5V
Date: 3/6/06
SP6656, 400mA Synchronous Buck Regulator with Dynamically Adjustable Voltage Output
© Copyright 2006 Sipex Corporation
4
TYPICAL PERFORMANCE CHARACTERISTICS
Refer to the typical application schematic, T
AMB
= +27°C
100
90
4.7uH Efficiency at 3.3Vout
(L1 = LQH32CN4R7)
100
90
Efficiency (%)
4.7uH Efficiency at 1.8Vout
(L1 = LQH32CN4R7)
Efficiency (%)
80
70
Vin=3.6V
80
70
60
50
Vin=3.0V
Vin=3.6V
Vin=4.2V
60
50
0.1
1
Vin=4.2V
10
Iout (mA)
100
1000
0.1
1
Iout (mA)
10
100
1000
100
90
4.7uH Efficiency at 3.3Vout
(L1 = LQH31CN4R7)
100
4.7uH Efficiency at 1.8Vout
(L1 = LQH31CN4R7)
Efficiency (%)
Efficiency (%)
90
80
70
60
50
Vin=3.0V
Vin=3.6V
Vin=4.2V
80
70
Vin=3.6V
60
50
0.1
1
Vin=4.2V
10
Iout (mA)
100
1000
0.1
1
10
Iout (mA)
100
1000
100
90
Efficiency (%)
Efficiency at 3.3Vout
(L1 = LQH2MCN4R7)
100
90
4.7uH Efficiency at 1.8Vout
(L1 = LQH2MCN4R7)
Efficiency (%)
80
70
60
50
0.1
1
10
Iout (mA)
100
1000
Vin=3.6V
Vin=4.2V
80
70
60
50
0.1
1
10
Iout (mA)
100
1000
Vin=3.0V
Vin=3.6V
Vin=4.2V
Date: 3/6/06
SP6656, 400mA Synchronous Buck Regulator with Dynamically Adjustable Voltage Output
© Copyright 2006 Sipex Corporation
5
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