SP6648ER-L [SIPEX]
Switching Regulator, Voltage-mode, 2A, MO-229VEED-5, LEAD FREE, DFN-10;
| 型号： | SP6648ER-L |
| 厂家： | 
SIPEX CORPORATION |
| 描述： | Switching Regulator, Voltage-mode, 2A, MO-229VEED-5, LEAD FREE, DFN-10 开关 |
| 文件： | 总16页 (文件大小：260K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
®
SP6648
Ultra-low Quiescent Current,
High Efficiency Boost Regulator
FEATURES
■ Ultra-low 12µA Quiescent Current
■ 400mA Output Current at 2.6V Input: 3.3VOUT
■ 94% Efficiency from 2 cell to 3.3VOUT
■ Wide Input Voltage Range: 0.95V to 4.5V
■ 3.3V Fixed or Adjustable Output
■ Integrated Synchronous Rectifier: 0.3Ω
■ 0.3Ω Switch
■ Anti-Ringing Switch Technology
■ Programmable Inductor Peak Current
■ Logic Shutdown Control
V
10
9
1
2
3
4
5
V
BATT
OUT
LBI
LX
SP6648
LBON
8
P
10 Pin DFN
GND
R
7
GND
LIM
SHDN
6
FB
Now Available in Lead Free Packaging
APPLICATIONS
■ Camera Flash LED Driver
■ Wireless Mouse
■ PDA's
■ Under Voltage Lock-Out at 0.61V
■ Programmable Low Battery Detect
■ Single or Dual Cell Alkaline
■ Pagers
■ Small 10 pin DFN Package and Industry
■ Medical Monitors
■ Handheld Portable Devices
■ MP3 Players
Standard 10 pin MSOP
DESCRIPTION
The SP6648 is an ultra-low quiescent current, high efficiency step-up DC-DC converter ideal for
single cell, dual cell alkaline and Li-Ion battery applications such as digital still cameras, PDA’s,
MP3 players, and other portable devices. The SP6648 combines the high delivery associated
withPWMcontrol,andthelowquiescentcurrentandexcellentlight-loadefficiencyofPFMcontrol.
TheSP6648features12µAquiescentcurrent, synchronousrectification, a0.3Ωchargingswitch,
anti-ringing inductor switch, programmable low battery detect, under-voltage lockout and
programmable inductor peak current. The device can be controlled by a 1nA active LOW
shutdown pin.
TYPICAL APPLICATION CIRCUIT
500
10µH
450
VBATT
400
+
350
300
47µF
SP6648
1
2
3
4
5
10
9
VOUT
VBATT
3.3VOUT
250
200
+
47µF
LX
PGND
GND
FB
LBI
LBI
1µF
8
LBON
RLIM
LBON
150
100
205K
47pF
7
6
SHDN
Vout=3.3V, Ipk=0.85A
Vout=5.0V, Ipk=0.85A
SHDN
50
0
1.87K
124K
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
Vin (V)
Maximum Load Current in Operation
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
1
ABSOLUTE MAXIMUM RATINGS
Operating Temperature ................................................ -40°C to +85°C
ESD Rating ........................................................................ 1.5kV HBM
LX, Vo, VBATT , LBON, FB to GND pin ................................ -0.3 to 6.0V
SHDN, LBI ........................................................... -0.3V to VBATT +1.0V
Vo, GND, LX Current ....................................................................... 2A
Reverse VBATT Current .............................................................. 220mA
Forward VBATT Current .............................................................. 500mA
Storage Temperature .................................................. -65 °C to 150°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 SPECIFICATIONS
VBATT =VSHDN = 2.6V, VFB=0V, ILOAD = 0mA, TAMB = -40°C to +85°C, VOUT = +3.3V, typical values at 27°C unless
otherwise noted. The ♦ denotes the specifications which apply over full operating temperature range -40°C to +85°C, unless
otherwise specified.
PARAMETER
MIN
0.7
TYP
MAX UNITS
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
CONDITIONS
Input Voltage Operating Range, VBATT
Output Voltage Range, VOUT
Start-up Input Voltage, VBATT
Under Voltage Lock-out/UVLO
Output Voltage, VO
4.5
5.5
V
V
After Startup
2.5
0.85
0.61
3.30
12
1.1
V
RLOAD = 3kΩ
0.5
0.7
V
3.12
3.48
25
V
Internal Feedback Divider
VOUT = 3.3V, VFB = 1.5V, Toggle SHDN
VOUT = 3.3V, VFB = 1.5V
VSHDN = 0V
Quiescent Current into VO, IQO
Quiescent Current into VBATT, IQB
Shutdown Current into VO, ISDO
Shutdown Current into VBATT, ISDB
Efficiency
µA
nA
nA
nA
250
1
750
500
750
250
VSHDN = 0V, VBATT = 2.6V
84
92
%
%
VBATT = 1.3V, IOUT = 100mA, RLIM =2kΩ
VBATT = 2.6V, IOUT = 200mA, RLIM =2kΩ
Inductor Current Limit, IPK = 1600/RLIM
Output Current
650
1300
800
1600
1000
2000
mA
mA
♦
♦
RLIM = 2kΩ
RLIM = 1kΩ
100
200
mA
mA
VBATT = 1.3V, RLIM = 4kΩ
VBATT = 2.6V, RLIM = 4kΩ
150
400
mA
mA
VBATT = 1.3V, RLIM =2kΩ
VBATT = 2.6V, RLIM =2kΩ
Minimum Off-Time Constant KOFF
Maximum On-Time Constant KON
Enable Valid to Output Stable
NMOS Switch Resistance
PMOS Switch Resistance
FB Set Voltage, VFB
0.5
2.5
1.0
4.0
1.5
5.5
V*µs
V*µs
µs
Ω
♦
♦
K
OFF ≤ TOFF (VOUT- VBATT
)
KON ≥ TON (VBATT
)
300
0.30
0.30
1.25
1
500
0.6
ILOAD = 1mA
♦
♦
♦
♦
♦
INMOS = 100mA
IPMOS = 100mA
0.6
Ω
1.19
0.56
1.31
100
0.66
V
External feedback
VFB =1.3V
FB Input Current
nA
V
LBI Falling Trip Voltage
0.61
25
LBI Hysteresis
mV
V
Low Output Voltage for LBON, VOL
Leakage current for LBON
0.4
1
♦
♦
VBATT = 1.3V, ISINK = 1mA
VBATT = 1.3V, VLBON = 3.3V
µA
SHDN Input Voltage, Note 1
VIL
VIH
VIL
VIH
0.25
0.5
♦
♦
♦
♦
VBATT = 1.3V
VBATT = 1.3V
VBATT = 2.6V
VBATT = 2.6V
1.0
2.0
V
SHDN Input Current
LX Pin Leakage
1
100
3
nA
♦
µA
Note 1: SHDN must transition faster than 1V/100mS for proper operation.
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
2
PIN DESCRIPTION
PIN NUMBER
PIN NAME
DESCRIPTION
Battery Voltage. The startup circuitry is powered by this pin. Battery
Voltage is used to calculate switch off time: tOFF = KOFF/ (VOUT
1
VBATT
-
VBATT). When the battery voltage drops below 0.61V the SP6648
goes into an undervoltage lockout mode (UVLO), where the part is shut
down.
2
LBI
Low Battery Input. LBI below 0.61V causes the SP6648 pin to pull
LBON pin down to ground. Use a resistor divider to program the low
voltage threshold for a specific battery configuration.
3
4
LBON
RLIM
Low Battery Output Not. Open drain NMOS output that sinks current
to ground when LBI is below 0.61V.
Current Limit Resistor. By connecting a resistor RLIM from this pin to
ground the inductor peak current is set by IPEAK=1600/RLIM. The range
for RLIM is 9kΩ (for 180mA) to 1.KΩ (for 1.6A).
5
6
SHDN
FB
Shutdown Not. Tie this pin high to VBATT, for normal operation. Pull
this pin to ground to disable all circuitry inside the chip. In shutdown
the output voltage will float down to a diode drop below the battery
voltage.
Feedback. Connect this pin to GND for fixed +3.3V operation.
Connect this pin to a resistor voltage divider between VOUT and GND
for adjustable output operation.
7
8
9
GND
PGND
LX
Ground. Connect to ground plane.
Power Ground. The inductor charging current flows out of this pin.
Inductor Switching Node. Connect one terminal of the inductor to the
positive terminal of the battery. Connect the second terminal of the
inductor to this pin. The inductor charging current flows into LX,
through the internal charging N-channel FET, and out the PGND pin.
10
VOUT
Output Voltage. The inductor current flows out of this pin during
switch off-time. It is also used as the internal regulator voltage supply.
Connect this pin to the positive terminal of the output capacitor.
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
3
FUNCTIONAL DIAGRAM
VBATT
LX
QKILL
charge end
IUC
V
O
undercurrent
comparator
INTERNAL
BATT
V
BATT
V
T
Min
T
OFF
OFF
INTERNAL
SUPPLY
VOUT
-
UVLO
QKILL
c
switch
buffer
SHDN
SDI
0.61V
+
PMOS
V
O
R
Q
V
CHARGE
BATT
NMOS
Max
Ton
n
Ref
Block
IBIAS
1.25V
REF
FB
SDI
+
-
VOLOW
S
c
LX
+
Qn
LOAD
c
current
reference
0.61V
-
+
c
overcurrent
comparator
-
FB
PGND
GND
SWITCH GROUND
current
control
current
reference
Ipkset
INTERNAL
GROUND
RLIM
LBON
-
LBI
c
0.61V
+
SP6648
THEORY OF OPERATION
Detailed Description
Control Scheme
The SP6648 is a step-up DC-DC converter that
can start up with input voltages as low as 0.85V
(typically) and operates with an input voltage
down to 0.61V. Ultra low quiescent current of
12µA provides excellent efficiency, up to 94%.
In addition to the main switch, a 0.3Ω internal
MOSFET the SP6648 has an internal synchro-
nous rectifier, increasing efficiency and reduc-
ing the space of an external diode. An internal
inductive-dampingswitchsignificantlyreduces
inductive ringing for low noise high efficiency
operation. If the supply voltage drops below
0.61V the SP6648 goes into under voltage lock-
out, thus opening both internal switches. An
externally programmable low battery detector
with open drain output provides the ability to
flag battery low condition. The inductor peak
current is externally programmable to allow for
a range of inductor values.
A minimum off-time, current limited pulse fre-
quencymodulation(PFM)controlschemecom-
bines the high output power and efficiency of a
pulse width modulation (PWM) device with the
ultra low quiescent current of the traditional
PFM. At low to moderate output loads the PFM
control provides higher efficiency than tradi-
tional PWM converters are capable of deliver-
ing. At these loads the switching frequency is
determined by a minimum off-time (tOFF
,
)
MIN
and a maximum on-time (tON, MAX) where:
t
t
OFF ≥ KOFF / (VOUT - VBATT) and
ON ≤ KON / VBATT with
KOFF = 1.0Vµs and
KON = 4.0Vµs.
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
4
THEORY OF OPERATION: Continued
At light loads (as shown in plot A in Figure 1)
thechargecyclewilllastthemaximumvaluefor
tON: For a 1V battery this would be as follows:
Inductor Current vs. Load
llim
E
Ton Max.
Toff Min.
E. Iripple=Toff* (Vo - Vi)/L
tON = KON / VBATT = 4.0Vµs / 1V = 4.0µs
llim
llim
llim
llim
Ton Max.
D
C
B
Toff Min.
The current built up in the coil during the charge
cycle gets fully discharged (discontinuous con-
duction mode DCM) When the current in the
coil has reached zero the synchronous rectifier
switch is opened and the voltage across the coil
(from VBATT to LX) is shorted internally to
eliminate inductive ringing.
D. Toff*= (Vo - Vi)/L<Iripple<Ton*Vi/L
Ton Max. Toff Min.
C. Iripple=Ton*Vi/L
B. Iripple=Ton*Vi/L
A. Iripple=Ton*Vi/L
Ton Max.
Toff Min.
With increasing load (as shown in plot B in
Figure 1) this inductor damping time becomes
shorter, because the output will quickly drop
below its regulation point due to heavier load. If
the load current increases further the SP6648
enters continuous conduction mode (CCM)
where there is always current flowing in the
inductor. The charge time remains at maximum
Ton Max. Toff Min.
A
Figure 1. Inductor Current vs. Load
which ends the charge cycle and starts the dis-
charge cycle. However, full load is not yet
achieved because at the end of the minimum
discharge time the output was still within regu-
lation.
t
ON as long as the inductor peak current limit is
not reached as shown in plot C in Figure 1. The
inductor peak current limit can be programmed
by tying a resistor RLIM from the RLIM pin to
ground where:
Maximum load is reached when this discharge
time has shrunk to the minimum allowed value
IPEAK = 1600 / RLIM
T
OFF as shown in Plot E of Figure 1.
When the peak current limit is reached the
charge time is short-cycled.
In plot D of Figure 1, the switch current reaches
the peak current limit during the charge period
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
5
TYPICAL PERFORMANCE CHARACTERISTICS
Refer to the Typical Application Circuit on page 1, TAMB=+25°C.
100
100
95
90
85
80
75
95
90
85
80
75
70
65
60
Vi=3.0V
Vi=2.6V
Vi=2.0V
Vi=1.3V
Vi=1.0V
Vi=4.2V
Vi=3.2V
Vi=2.6V
Vi=2.0V
Vi=1.6V
Vi=1.0V
70
65
60
0.1
1.0
10.0
100.0
1000.0
0.1
1.0
10.0
100.0
1000.0
Iload (mA)
Iload (mA)
Efficiency vs. Current Load, VOUT=5.0V
Efficiency vs. Load Current, VOUT=3.3V
3.400
3.380
5.100
5.080
5.060
Vi=3.0V
Vi=2.6V
Vi=2.0V
Vi=1.3V
Vi=1.0V
Vi=4.2V
Vi=3.2V
Vi=2.6V
Vi=2.0V
Vi=1.6V
Vi=1.0V
3.360
3.340
3.320
5.040
5.020
5.000
3.300
3.280
4.980
4.960
4.940
4.920
4.900
3.260
3.240
3.220
3.200
0
100
200
300
400
500
0
100
200
300
400
500
Iload (mA)
ILOAD(mA)
Line/Load Rejection vs. Load Current, VOUT = 3.3V
Line/Load Rejection vs. Load Current, VOUT = 5.0V
100
300
250
80
60
200
150
100
40
20
50
0
0
1.0
1.5
2.0
2.5
Vin (V)
3.0
3.5
4.0
4.5
1.0
1.5
2.0
2.5
3.0
Vin (V)
No Load Battery Current, VOUT=3.3V
No Load Battery Current, VOUT=5.0V
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
6
TYPICAL PERFORMANCE CHARACTERISTICS
Refer to the Typical Application Circuit on page 1, TAMB=+25°C.
400
350
300
500
450
400
350
250
200
300
250
200
150
100
50
150
100
50
0
0
1.0
1.5
2.0
2.5
3.0
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
Vin (V)
Vin (V)
Maximum Resistive Load Current in Startup, VOUT=3.3V
Maximum Resistive Load Current in Startup, VOUT=5.0V
V
(AC)
OUT
VOUT (AC)
Inductor Current
(0.2A/DIV)
Inductor Current
(0.2A/DIV)
Output Ripple, VIN=2.6V, ILOAD=200mA, VOUT=3.3V
Output Ripple, VIN=2.6V, ILOAD=200mA, VOUT=5.0V
5.0
5.0
4.0
4.0
3.0
2.0
3.0
2.0
1.0
1.0
0.0
0.0
0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 3.3
0.9
1.4
1.9
2.4
2.9
3.4
3.9
4.4
4.9
Vin (V)
Vin (V)
KON vs. VIN , VOUT=3.3V
KON vs. VIN , VOUT=5.0V
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
7
TYPICAL PERFORMANCE CHARACTERISTICS
Refer to the Typical Application Circuit on page 1, TAMB=+25°C.
2.0
2.0
1.5
1.0
0.5
0.0
1.5
1.0
0.5
0.0
0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 3.3
0.9
1.4
1.9
2.4
2.9
3.4
3.9
4.4
4.9
Vin (V)
Vin (V)
KOFF vs. VIN , VOUT=5.0V
KOFF vs. VIN , VOUT=3.3V
V
IN
V
IN
V
OUT
V
OUT
I
IN
(1A/div)
I
(1A/div)
IN
Startup, VIN=2.6V, VOUT=3.3V, RLOAD = 100Ω
Startup, VIN=4.2V, VOUT=5.0V, RLOAD = 100Ω
V
(AC)
OUT
VOUT(AC)
LX
LX
I
(0.5A/DIV)
OUT
IOUT(0.2A/div)
Load Step, 0.1A to 0.3A, VIN = 2.6V, VOUT = 3.3V
Load Step, 0.3A to 0.5A, VIN = 4.2V, VOUT = 5.0V
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
8
APPLICATIONS INFORMATION
Circuit Layout
ripple for the SP6648 to regulate the output.
Designers should select input and output ca-
pacitors with a rating exceeding the inductor
current ripple, which is typically set by the
inductor value and the KON value as given in the
following relationship:
Printed circuit board layout is a critical part of a
power supply design. Poor designs can result in
excessive EMI on the feedback paths and on the
ground planes with applications involving high
switching frequencies and large peak currents.
Excessive EMI can result in instability or regu-
lation errors. All power components should be
placed on the PC board as closely as possible
with the traces kept short, direct, and wide
(>50mils or 1.25mm). Extra copper on the PC
board should be integrated into ground as a
pseudo-groundplane.OnamultilayerPCboard,
routethestargroundusingcomponent-sidecop-
per fill, then connect it to the internal ground
plane using vias. For the SP6648 devices, the
inductor and input and output filter capacitors
should be soldered with their ground pins as
close together as possible in a star-ground con-
figuration. The VOUT pin must be bypassed di-
rectly to ground as close to the SP6648 devices
as possible (within 0.2in or 5mm). The DC-DC
converter and any digital circuitry should be
placed on the opposite corner of the PC board as
far away from sensitive RF and analog input
stages. Noisy traces, such as from the LX pin,
should be kept away from the voltage-feedback
IL(RIPPLE) = KON/L
For the example of the 10µH inductor the induc-
torcurrentripplewouldbe330mA, whileforthe
22µH inductor the inductor current ripple value
would be 150mA. Do not allow tantalum ca-
pacitors to exceed their ripple-current ratings.
An input filter capacitor can reduce peak cur-
rents drawn from the battery and improve effi-
ciency. For most applications, use the same
47µF tantalum capacitor as used for the input.
Low-ESR aluminum electrolytic capacitors are
acceptable provided they meet the ESR require-
ment of 0.2Ω to 0.3Ω, and we list an appropriate
100µF aluminum electrolytic in the component
selection table, but standard aluminum electro-
lytic capacitors are not recommended.
In selecting an inductor, the saturation current
specified for the inductor needs to be greater
thentheSP6648peakcurrenttoavoidsaturating
the inductor, which would result in a loss in
efficiency and could damage the inductor. The
SP6648 evaluation board uses a Sumida
CDRH5D28 10µH inductor with an ISAT value
of 1.3A and a DCR of 0.065Ω, which easily
handles the IPEAK of 0.85A of the SP6648 and
will deliver high efficiencies. Other inductors
could be selected provided their ISAT is greater
than the IPEAK of the SP6648.
V
OUTnodeandseparatedfromitusinggrounded
copper to minimize EMI. See the SP6648EB
Evaluation Board Manual for PC Board Layout
design details.
Component Selection
Selection of capacitors for SP6648 power sup-
ply circuits can be made through the use of the
Component Selection Table. Capacitor equiva-
lent series resistance (ESR) in the range of 0.2Ω
to 0.3Ω is a requirement for obtaining sufficient
output voltage ripple for the SP6648 to properly
regulate under load. For ESR values in this
range, low ESR Tantalum capacitors are recom-
mended. For example, in the SP6648 applica-
tion circuit a 47µF, 10V, low-ESR, surface-
mount tantalum output filter capacitor typically
provides 50mV output ripple when stepping up
from 2.6V to 3.3V at 200mA. Ceramic capaci-
tors have ESR too low to produce enough output
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
9
APPLICATIONS INFORMATION: Continued
INDUCTORS - SURFACE MOUNT
Inductor Specification
Inductance Manufacturer/Part No.
H)
Series R
ISAT
(A)
Size LxWxH
(mm)
Intuctor Type
Manufacturer
Website
(
µ
Ω
10
10
10
22
22
22
Sumida CDRH5D28-100
TDK RLF5018T-100MR94
Sumida CD43-100
0.065
0.067
0.180
0.122
0.067
0.378
1.30
0.94
1.04
0.90
0.63
0.68
5.7x5.5x3.0
5.6x5.2x2.0
4.0x4.5x3.5
5.7x5.5x3
Shielded Ferrite Core
Shielded Ferrite Core
Unshileded Ferrite Core
Shileded Ferrite Core
Shielded Ferrite Core
Unshielded Ferrite Core
www.sumida.com
www.tdk.com
www.sumida.com
www.sumida.com
www.tdk.com
Sumida CDRH5D28-220
TDK RLF5018T-220MR63
Sumida CD43-220
5.6x5.2x2.0
4.0x4.5x3.5
www.sumida.com
CAPACITORS - SURFACE MOUNT & LEADED
Capacitor Specification
Capacitance Manufacturer Part No.
F)
ESR
Ripple Current Size LxWxH Voltage
Capacitor
Type
Manufacturer
Website
(
µ
Ω(max)
(A) @ 85°C
(mm)
(V)
10
10
25
47
Kemet T494C476K010AS 0.300
1.06
6.0x3.2x2.5
7.3x4.3x2.0
6.3DX11L
SMT Tantalum
SMT Tantalum
www.kemet.com
www.kemet.com
47
Kemet T494V476K010AS
Sanyo 25MV100AX
0.300
0.220
0.99
100
0.30
Radial Al Electrolytic www.sanyovideo.com
Note: Components highlighted in bold are those used on the SP6648EB Evaluation Board.
Component Selection Table
VBATT
L1
10µH
C1
R5 1.0M
+
R
3
549K
47µF
U1 SP6648
3.3VOUT
1
2
3
4
5
10
9
VBATT
VOUT
LX
C4
1µF
LBI
R4
LBON
R1
8
+
249K
C3
C2
LBON
RLIM
PGND
GND
FB
205K
7
47pF
47µF
6
SHDN
R2
RLIM
1.87K
124K
SP6648EB Evaluation Board Schematic
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
10
APPLICATIONS INFORMATION : Continued
VOUT Programming
output goes low as determined by the relation-
ship:
The SP6648 can be programmed as either a
voltage source or a current source. To program
the SP6648 as voltage source, the SP6648 re-
quires 2 feedback resistors R1 & R2, as shown
intheSP6648EBevaluationboardschematic, to
control the output voltage. To set VOUT in the
voltage mode, use the equation:
VLOWBATT = 0.61 * [(R3 + R4)/R4]
The SP6648 evaluation board R3 & R4 resistors
have been set to trip for a falling battery thresh-
old of about 2.0V. Using this relationship, other
low battery threshold values can be set by the
user.
R1 = [(VOUT/1.25)-1] * R2
Using the RLIM Function
UVLO the Under Voltage Lock-Out Function
Thepeakinductorcurrent,IPEAK,isprogrammed
externally by the RLIM resistor connected be-
tweentheRLIMpinandGND. Thepeakinductor
current is defined by:
Once started up, the SP6648 will regulate the
output until the input battery is completely dis-
charged or until the under voltage lock-out
(UVLO) occurs at VBATT = 0.61V. The UVLO
function will completely open all switches until
the battery again rises above the 0.61V thresh-
old.
I
PEAK = 1600/RLIM
The saturation current specified for the inductor
needstobegreaterthanthepeakcurrenttoavoid
saturating the inductor, which would result in a
loss in efficiency and could damage the induc-
tor. The SP6648 evaluation board uses a RLIM
value of 1.87K for an IPEAK = 850mA to allow
the circuit to deliver up to 180mA for 1.3V input
and 400mA for 2.6V input. Other values could
be selected using the above relationships.
Maximum Startup Current
It should be noted that for low input voltages the
SP6648 startup circuit can not support large
load currents at startup. In startup the SP6648
needs to boost the output from zero volts using
theinputvoltage. Oncetheoutputisgreaterthan
1.9V the operate circuit takes over and the
SP6648 can supply much more current. Curves
of maximum load current in startup for the
SP6648 are shown in the typical performance
characteristics and can be compared with the
page one curve for maximum load current in
operation.
Using the LBON - Low Battery Output
Function
The SP6648 will regulate the output until the
input battery is completely discharged or until
the under voltage lock-out (UVLO) occurs at
VBATT = 0.61V. To provide a low battery warn-
ing, the Low Battery Output function of the
SP6648 can be used. LBON is programmed
externally by the R3 and R4 resistor divider
connected between VBATT , the LBI input pin
and GND. The LBON is an open drain output,
which is active low and is pulled up by a 1M
resistor R5 to VOUT. When the LBI comparator
falling threshold of 0.61V is reached, the LBON
For1-cellbatteryapplications,itisrecommended
to apply any large load current after the SP6648
has started up, typically in a few milliseconds.
This is typically not a problem in many applica-
tions where the load is a processor whose load
current is low until the processor voltage comes
up.
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
11
APPLICATIONS INFORMATION
SP6648LEDEB Evaluation Board with
LumiLED High Brightness White LED
where VREF is around 0.61V, IF is the operating
current of the LumiLED. To set the operating
current to be about 350mA, Rb is selected as 1.8 Ω
as shown in the following schematic. The effi-
ciency of the SP6648 LumiLED circuit is im-
proved by the use of a silicon diode D1 and
resistor R1 to set the voltage at the current sense
resistor R2 to 0.61V instead of the higher 1.25V
at the FB pin. An efficiency curve follows
showing the SP6648 efficiency driving 350mA
outputcurrentintothehighbrightnessLumiLED.
For the high brightness LumiLED white LED
application,theSP6648isgenerallyprogrammed
as a current source. The bias resistor Rb is used
to set the operating current of the white LED as
equation:
Rb = VREF/IF
VBATT
L1
10µH
1.8-3.2V
Important:
1µF Ceramic Cap at V
Pin
OUT
needed for stable regulation
C1
10µF
1
2
3
4
5
10
9
VBATT
LBI
VOUT
C4
SP6648
1µF
R1
C2
10µF
LX
D2
8
16.2k
1W LED
350mA
LBON
RLIM
PGND
GND
FB
7
6
R5 10K
D1 1N4148
SHDN
V
= 0.61V
REF
R
1.87K
LIM
(R5 optional)
Rb
1.8Ω
IOUT=0.61V/R
b
SP6648LEDEB Evaluation Board Schematic
100
95
As shown in following scope photos, if the
SP6648 is powered up before the LumiLED is
plugged in, the circuit will bring the Feedback
pin to 0V and the SP6648 has a feature to set the
outputvoltagetobe3.3V. OncetheLumiLEDis
pluggedin, theFeedbackpinwillgoupto1.25V
andbegintoregulate. Theoutputvoltagewillgo
from 3.3V to 3.68V (=VF+0.61V), where VF is
the forward voltage of the LumiLED. When the
LumiLED is open, the Feedback pin voltage
will go to 0V and the output voltage will go to
3.3V which will protect the part.
90
85
80
75
70
65
60
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
Battery Voltage (V)
SP6648LEDEB Efficiency Curve
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
12
APPLICATIONS INFORMATION
V
OUT
V
OUT
V
REF
V
REF
Plug in the LumiLED
Unplug the LumiLED
Brightness Control
One approach to control LED brightness is to
apply a PWM signal to the SHDN input of the
SP6648. In this case, the output current will be
equal to the product of 350mA and the average
duty cycle at the SHDN pin. An optional 10K
potentiometer (R5) may also be used for dim-
mingtheLEDcurrentbyvaryingthepotentiom-
eter between low brightness and full brightness.
PINOUTS
VBATT
1
10
V
VOUT
LX
10
9
1
2
3
4
5
V
BATT
LBI
OUT
LBI
LBON
RLIM
9
8
7
6
2
3
4
5
LX
P
SP6648
SP6648
LBON
PGNDV
8
10 Pin DFN
GND
10 Pin MSOP
R
GND
FB
7
GND
LIM
SHDN
SHDN
6
FB
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
13
PACKAGE: 10 PIN MSOP
D
e1
Ø1
R1
R
E/2
Gauge Plane
L2
E
E1
Ø
Ø1
Seating Plane
L
L1
1
2
e
Pin #1 indentifier must be indicated within this shaded area (D/2 * E1/2)
B
B
10 Pin MSOP JEDEC MO-187 (BA) Variation
MIN
NOM
MAX
SYMBOL
A
A1
A2
b
-
0
0.75
0.17
0.08
-
-
1.1
0.15
0.95
0.27
0.23
0.85
-
-
c
D
3.00 BSC
A2
A
E
4.90 BSC
E1
e
3.00 BSC
0.50 BSC
b
A1
e1
L
2.00 BSC
0.4
0.6
0.8
L1
L2
N
R
R1
ø
0.95 REF
0.25 BSC
b
-
10
-
-
-
-
-
-
-
8º
15º
WITH PLATING
0.07
0.07
0º
ø1
0º
c
Note: Dimensions in (mm)
BASE METAL
Section B-B
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
14
PACKAGE: 10 PIN DFN
D
A3
D/2
E/2
E
A1
Top View
A
Side View
3x3 10 Pin DFN JEDEC MO-229 (VEED-5)
VARIATION
D2
2
1
MIN
0.8
0
NOM
0.9
0.02
0.65
0.20 REF
0.25
3.00 BSC
MAX
1
0.05
0.8
SYMBOL
A
A1
A2
A3
b
D
D2
e
0.55
0.18
2.2
0.3
2.7
E2
0.5 PITCH
E
3.00 BSC
E2
K
L
1.4
0.2
0.3
-
-
0.4
1.75
-
0.5
K
L
b
e
Note: Dimensions in (mm)
Bottom View
Date: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
15
ORDERING INFORMATION
Part Number
Top Mark
Operating Temperature Range
Package Type
SP6648EU ................................ SP6648EU..................-40°C to +85°C ...................................... 10 Pin MSOP
SP6648EU/TR .......................... SP6648EU..................-40°C to +85°C ..................................... 10 Pin MSOP
SP6648ER ............................... SP6648ERYWW..........-40°C to +85°C ........................................ 10 Pin DFN
SP6648ER/TR ......................... SP6648ERYWW..........-40°C to +85°C ....................................... 10 Pin DFN
Available in lead free packaging. To order add "-L" suffix to part number.
Example: SP6648EU/TR = standard; SP6648EU-L/TR = lead free
/TR = Tape and Reel
Pack quantity is 2,500 for MSOP and 3,000 for DFN.
CLICK HERE TO ORDER SAMPLES
Corporation
ANALOGEXCELLENCE
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: 1/19/05
SP6648 Ultra-low Quiescent Current, High Efficiency Boost Regulator
© Copyright 2005 Sipex Corporation
16
相关型号：
©2020 ICPDF网 联系我们和版权申明