®
SP6655
Ideal for portable designs powered with Li Ion battery
High Efficiency 400mA Synchronous Buck Regulator
FEATURES
■
98% Efficiency Possible
■
Small 10-Pin DFN Package
■
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
P
VIN
VIN
BLON
D1
D0
1
2
3
4
5
10
SP6655
10 Pin DFN
LX
9
P
GND
8
GND
7
V
OUT
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 SP6655 is a 400mA synchronous buck regulator which is ideal for portable applications that
use a Li-Ion or 3 cell alkaline/NiCD/NiMH input. The SP6655’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 SP6655
seamlessly transitions into 100% duty ratio operation, further extending useful battery life. The
SP6655 is protected against overload and short circuit conditions with a precise inductor peak
current limit. Other features include programmable under voltage lockout and low battery
detection, externally programmed output voltage down to 1.0V, logic level shutdown control, and
140°C over temperature shutdown.
TYPICAL APPLICATION SCHEMATIC
2.7V to 5.5V Input
VI
L1
10µH
10Ω
R
VIN
CV
IN
1µF
V
OUT
400mA
VO
C
IN
10µF
1M
SP6655
P
VIN
V
IN
BLON
LX
P
GND
GND
C
OUT
10µF
CF
R
F
22pF
BLON
D1
D0
D1
D0
V
OUT
FB
R
I
200K
Date: 09/27/05
SP6655 High Efficiency 400mA Synchronous Buck Regulator
© Copyright 2004 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
SDN
=3.6V, V
OUT
=V
FB
, I
O
= 0mA, T
AMB
= -40°C to +85°C, typical values at 27°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
Battlo Trip Voltage, V
IN
falling
Battlo Trip Voltage Hysteresis
BLON Low Output Voltage
BLON Leakage Current
Over-Temperature
Rising Trip Point
Over-Temperature Hysteresis
D1,D0 Leakage Current
D1,D0 Input Threshold Voltage
FB Leakage Current
LX Leakage
MIN
UVLO
1.0
0.784
TYP
MAX
5.5
UNITS
V
V
V
CONDITIONS
Result of I
Q
measurement at V
IN
=PV
IN
=5.5V
0.800
0.816
1.5
1.6
2.25
2.4
100
200
0.3
0.3
625
96
92
500
20
1
2
1
2.70
2.85
3.00
40
300
9
±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
2.55
2.70
2.85
265
30
500
5
500
2.85
3.00
3.15
335
0.4
1
µA
nA
µA
nA
V
mV
mV
mV
V
µA
°C
°C
nA
V
V
nA
µA
V
OUT
=3.3V, V
IN
=3.6V and V
IN
= 5.5V
D1=D0=0V
V
OUT
= 3.3V
D1=D0=0V
D1=0V, D0=V
IN
D1=V
IN
, D0=0V
D1=V
IN
, D0=V
IN
Measured as V
IN
-V
OUT
V
IN
=3.3V, I
SINK
=1mA
V
BLON
=3.6V
140
14
1
0.90
1.25
1
3
500
1.8
100
5
0.60
High to Low Transition
Low to High Transition
FB=1V
D1,D0=0V, V
IN
=3.6V
LX=0V,LX=V
IN
+0.2V
Date: 09/27/05
SP6655 High Efficiency 400mA Synchronous Buck Regulator
© Copyright 2004 Sipex Corporation
2
PIN DESCRIPTION
PIN NUMBER
1
2
3
4
5
6
PIN NAME
P
VIN
V
IN
BLON
D1
D0
FB
DESCRIPTION
Input voltage power pin. Inductor charging current passes through this pin.
Internal supply voltage. Control circuitry powered from this pin.
Open drain battery low output. (V
IN
-V
O
) less than 300mV pulls this
node to ground. (V
IN
-V
O
) above threshold, this node is open.
Digital mode control input. See table I for definition.
Digital mode control input. See table I for definition.
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.
7
8
9
10
V
OUT
GND
P
GND
LX
D1
0
0
1
1
D0
0
1
0
1
Shutdown. All internal circuitry is disabled and the power switches are opened.
Device enabled, falling UVLO threshold =2.70V
Device enabled, falling UVLO threshold =2.85V
Device enabled, falling UVLO threshold =3.00V
Table 1. Operating Mode Definition
FUNCTIONAL DIAGRAM
V
IN
DRVON
VOLOW
T
ONOVER
MIN Ton
Internal Supply
T
ONOVER
REF
+
V
OUT
P
VIN
Min Ton
Min T
ON
=
K
ON
/(V
IN
-V
OUT
)
M
DRVON
R
S
Q
1
OVR_I
Vos
-
REF'
+
-
VOLOW
+
DRIVER
C
ILIM/M
V
RAMP
_
Q
-
C
FB
+
-
FB'
RST
OVR_I
LX
DRVON
REF
Ref
Block
UVLO
TSD
D0
D1
+
One-Shot
=100ns
BLANK
-
C
Zero_X
P
GND
T
OFF
=
K
OFF
/V
OUT
ILIM/M
OVR_I
GND
V
OUT
V
IN
-
300mV
+
+
-
BLON
C
DRVON
BLANK
BLANK = T
BLANK
(=100ns) or T
OFF
= K
OFF
/V
OUT
UVLO
Date: 09/27/05
SP6655 High Efficiency 400mA Synchronous Buck Regulator
© Copyright 2004 Sipex Corporation
3
TYPICAL PERFORMANCE CHARACTERISTICS
Refer to the typical application schematic, T
AMB
= +27°C
100
95
90
85
Efficiency (%)
Efficiency (%)
100
95
90
85
80
75
70
Vi=3.6V
Vi=3.9V
Vi=4.2V
Vi=5.0V
80
75
0.1
1.0
10.0
ILoad (mA)
100.0
1000.0
65
60
0.1
1.0
10.0
ILoad (mA)
100.0
1000.0
Efficiency vs. Load, V
OUT
=3.3V, V
IN
=3.6V
Efficiency vs Load, V
OUT
= 1.5V
3.45
Vi=3.6V
Vi=3.9V
Vi=4.2V
Vi=5.0V
1.55
Vi=3.6V
Vi=3.9V
Vi=4.2V
Vi=5.0V
3.40
1.53
3.35
Vout (V)
1.51
3.30
Vout (V)
1.49
3.25
1.47
3.20
3.15
0
100
200
300
400
500
ILoad (mA)
1.45
0
100
200
300
400
500
ILoad (mA)
Line/Load Rejection, V
OUT
= 3.3V
Line/Load Rejection, V
OUT
= 1.5V
500
50
400
Tamb = 85°C
Tamb = 25°C
Tamb = -40°C
40
Tamb = 85°C
Tamb = 25°C
Tamb = -40°C
300
Iin (uA)
30
Iin(µA)
200
20
100
10
0
3.0
3.3
3.6
Vin (V)
3.9
4.2
0
3.0
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: 09/27/05
SP6655 High Efficiency 400mA Synchronous Buck Regulator
© Copyright 2004 Sipex Corporation
4
TYPICAL PERFORMANCE CHARACTERISTICS
Refer to the typical application schematic, T
AMB
= +27°C
3.5
3.0
2.5
3.5
3.0
2.5
Kon (V*usec)
Kon (V*usec)
2.0
1.5
1.0
0.5
0.0
3.6
2.0
1.5
1.0
0.5
3.9
4.2
4.5
Vin (V)
4.8
5.1
5.4
0.0
3.0
3.3
3.6
3.9
4.2 4.5
Vin (V)
4.8
5.1
5.4
K
ON
vs V
IN
, V
OUT
=3.3V
K
ON
vs V
IN
, V
OUT
=1.5V
3.5
3.0
2.5
Koff (V*usec)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
3.6
Koff (V*usec)
2.0
1.5
1.0
0.5
3.9
4.2
4.5
Vin (V)
4.8
5.1
5.4
0.0
3.0
3.3
3.6
3.9
4.2
Vin (V)
4.5
4.8
5.1
5.4
K
OFF
vs V
IN
, V
OUT
=3.3V
K
OFF
vs V
IN
, V
OUT
=1.5V
700.0
700.0
600.0
600.0
500.0
Frequency (KHz)
Frequency (KHz)
500.0
400.0
400.0
300.0
300.0
200.0
Vout = 3.3V
Measured
Vout = 3.3V
Calculated
4.0
Vin (V)
4.5
5.0
200.0
Vout = 1.5V
Measured
Vout = 1.5V
Calculated
3.4
3.8
4.2
Vin (V)
4.6
5.0
100.0
100.0
0.0
3.5
0.0
Ripple Frequency vs. V
IN
, I
OUT
=0.4A, V
OUT
=3.3V
Ripple Frequency vs. V
IN
, I
OUT
=0.4A, V
OUT
=1.5V
Date: 09/27/05
SP6655 High Efficiency 400mA Synchronous Buck Regulator
© Copyright 2004 Sipex Corporation
5
