1
Rev. 3/5/02,
*Patent Pending
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
Copyright 2002 Sipex Corporation
DESCRIPTION
The SP6641 is an ultra-low quiescent current, high efficiency, DC-DC boost converter designed
for single and dual cell alkaline, or Li-ion battery applications found in PDA's, MP3 players, and
other handheld portable devices. The SP6641 features a 10
A quiescent current, a 0.3
N-
channel charging switch, 0.9V input startup, and a 0.33A or 1.0A inductor current limiting feature.
The SP6641 is offered in a 5 pin SOT-23 package and provides an extremely small power supply
footprint optimized for portable applications. The SP6641 is preset to 3.3V and can be controlled
by a 1nA active LOW shutdown pin.
500mA Alkaline DC/DC Boost Regulator in SOT-23
s
Ultra Low Quiescent Current: 10
A
s
Wide Input Voltage Range: 0.9V to 4.5V
s
90mA I
OUT
at 1.3V Input (SP6641A-3.3V)
s
500mA I
OUT
at 2.6V Input (SP6641B-3.3V)
s
100mA I
OUT
at 2.0V Input (SP6641A-5.0V)
s
500mA I
OUT
at 3.3V Input (SP6641B-5.0V)
s
Fixed 3.3V or 5.0V Output Voltage
s
Up to 87% Efficiency
s
0.3
NFET R
DS
on
s
Startup Voltage Guaranteed at 0.9V
s
0.33A Inductor Current Limit (SP6641A)
s
1A Inductor Current Limit (SP6641B)
s
Logic Shutdown Control
s
SOT-23-5 Package
V
OUT
GND
SHDN
V
BATT
LX
SP6641
5 Pin SOT-23
1
2
3
5
4
APPLICATIONS
s
PDA's
s
DSC's
s
CD/MP3 Players
s
Pagers
s
Digital Cameras
s
Portable Handheld Medical Devices
SP6641A/6641B
Figure 1. Typical Application Schematic
Figure 2. Maximum Load Current in Operation
I
OUT
(mA)
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
V
IN
(V)
SP6641B, 1.0A, 3.3V
SP6641B, 1.0A, 5V
SP6641A, 0.33A, 3.3V
SP6641A, 0.33A, 5V
GND
LX
V
BATT
SHDN
L1
0.9V to 4.5V
U1
SP6641A
V
OUT
SHDN
V
BATT
C2
V
OUT
+3.3V or 5V
D1
1
2
3
C1
5
4
C3
R1
SP6641A 3.3V & 5V: C1 = C2 = 22
F Ceramic, L1 = 22
H CDRH5D28,
D1 = MBR0520, C3 = Open, R1 = Shorted.
SP6641B 3.3V & 5V: C1 = C2 = 100
F POSCAP, L1 = 10
H CDRH5D28,
D1 = ZHCS2000, C3 = 1
F Ceramic, R1 = 10
.
2
Rev. 3/5/02,
*Patent Pending
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
Copyright 2002 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.
ELECTRICAL SPECIFICATIONS
V
BATT
= V
SHDN
= 1.3V, I
LOAD
= 0mA, -40
C <T
A
< +85
C, V
OUT
= +3.3V or +5.0V preset, typical values at 27
C
unless otherwise noted.
LX, V
OUT
, SHDN, V
BATT
to GND pin ....... -0.3 to 6.0V
LX Current .......................................................... 1.5A
Reverse V
BATT
Current ................................... 220mA
Storage Temperature ........................ -65
C to 150
C
Operating Temperature ..................... -40
C to +85
C
Lead Temperature (Soldering, 10 sec) .......... 300
C
PARAMETER
MIN
TYP
MAX
UNITS
CONDITIONS
Input Voltage Operating Range,
0.5
4.5
V
after startup
V
BATT
Startup Voltage, V
BATT
0.85
0.90
V
R
LOAD
=3k
, T
A
=27
C
1.00
V
R
LOAD
=3k
,-40
C <T
A
< +85
C
Output Voltage, V
OUT
3.16
3.30
3.44
V
3.3V V
OUT
preset
4.80
5.00
5.20
V
5.0V V
OUT
preset
Quiescent Current into V
OUT
,
10
15
A
V
OUT
=3.5V, 3.3V V
OUT
preset
I
Q(OUT)
V
OUT
=5.5V, 5.0V V
OUT
preset
Quiescent Current into V
BATT
,
250
500
nA
V
OUT
=3.5V, 3.3V V
OUT
preset
I
QB
V
OUT
=5.5V, 5.0V V
OUT
preset
Shutdown Current into V
OUT
,
1
500
nA
V
SHDN
=0V
I
SHDN
Shutdown Current into V
BATT
,
20
100
nA
V
SHDN
=0V
I
SHDN
Inductor Current Limit
280
330
380
mA
(SP6641A)
Inductor Current Limit
850
1000
1150
mA
(SP6641B)
Output Current (SP6641AEK-3.3)
90
mA
V
BATT
=1.3V
190
mA
V
BATT
=2.6V
Output Current (SP6641BEK-3.3)
200
mA
V
BATT
=1.3V
500
mA
V
BATT
=2.6V
Output Current (SP6641AEK-5.0)
100
mA
V
BATT
=2.0V
175
mA
V
BATT
=3.3V
Output Current (SP6641BEK-5.0)
275
mA
V
BATT
=2.0V
500
mA
V
BATT
=3.3V
Minimum Off-Time Constant
1.50
V*
s
T
OFF
K
OFF
/ (V
OUT
V
IN
)
K
OFF
NMOS Switch Resistance
0.3
0.75
Inmos=100mA
SHDN Input Voltage
Vil
20
%
% of V
BATT
Vih
80
%
% of V
BATT
SHDN Input Current
1
100
nA
3
Rev. 3/5/02,
*Patent Pending
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
Copyright 2002 Sipex Corporation
PIN DESCRIPTION
PIN NO.
PIN NAME
DESCRIPTION
1
LX
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 through the GND
pin.
2
GND
Ground pin. The internal regulator bias currents and the inductor
charging current flows out of this pin.
3
V
OUT
Output voltage sense pin, internal regulator voltage supply, and
minimum off-time one shot input. Kelvin connect this pin to the positive
terminal of the output capacitor, but for SP6641B, use 10
series
resistor and 1
F bypass per Figure 1 schematic.
4
SHDN
Shutdown. Tie this pin to V
BATT
for normal operation. Tie this pin the
ground to disable all circuitry inside the chip. In shutdown mode, the
output voltage will float at a diode drop below the battery potential.
5
V
BATT
Battery voltage pin. The startup circuitry runs off of this pin. The
regulating circuitry also uses this voltage to control the minimum off-
time. T
OFF
K
OFF
/ (V
OUT
V
IN
).
BLOCK DIAGRAM
Internal
V
BATT
V
BATT
Internal
Supply
SHDN
V
OUT
Ref
Block
REFREADY
REF
GND
Internal
Ground
I
PK
/M
V
OUT(LOW)
LX
+
-
C
SU
OSC
EN
Min.
T
OFF
+
-
C
FB
SHDN
V
BATT
V
OUT
V
OUT
SHDN
V
OUT
NGATE
DRIVER
CHARGE
R
Q
S
Qn
T
OFF
SUGATE
V
BATT
V
OUT
LX
M
1
ICHN
SP6641
LOAD
V
BATT
V
OUT
ITH
4
Rev. 3/5/02,
*Patent Pending
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
Copyright 2002 Sipex Corporation
PERFORMANCE CHARACTERISTICS
Refer to the circuit in Figure 1, T
AMB
= +25
C
60
65
70
75
80
85
90
95
100
0.1
1.0
10.0
100.0
1000.0
Iload (mA)
V
IN
= 3.0V
V
IN
= 2.6V
V
IN
= 2.0V
V
IN
= 1.3V
V
IN
= 1.0V
Efficiency (%)
60
65
70
75
80
85
90
95
100
0.1
1.0
10.0
100.0
1000.0
Iload (mA)
Efficiency (%)
V
IN
= 3.0V
V
IN
= 2.6V
V
IN
= 2.0V
V
IN
= 1.3V
V
IN
= 1.0V
3.200
3.220
3.240
3.260
3.280
3.300
3.320
3.340
3.360
3.380
3.400
Iload (mA)
0
50
100
150
200
250
V
OUT
V
IN
= 3.0V
V
IN
= 2.6V
V
IN
= 2.0V
V
IN
= 1.3V
V
IN
= 1.0V
3.220
3.240
3.260
3.280
3.300
3.320
3.340
3.360
3.380
3.400
0
200
400
600
800
3.200
Iload (mA)
V
OUT
V
IN
= 3.0V
V
IN
= 2.6V
V
IN
= 2.0V
V
IN
= 1.3V
V
IN
= 1.0V
Figure 3. SP6641AEK - 3.3 Efficiency vs Load Current
Figure 4. SP6641BEK - 3.3 Efficiency vs Load Current
Figure 5. SP6641AEK - 3.3 Line/Load Rejection vs Load
Current
Figure 6. SP6641BEK - 3.3 Line/Load Rejection vs Load
Current
Figure 7. SP6641AEK-5.0 Efficiency Vs Load Current
Figure 8. SP6641BEK-5.0 Efficiency Vs Load Current
Iload (mA)
Efficiency (%)
60
65
70
75
80
85
90
95
100
0.1
1.0
10.0
100.0
1000.0
Vi=4.2V
Vi=3.6V
Vi=3.3V
Vi=2.0V
Vi=1.3V
Iload (mA)
Efficiency (%)
60
65
70
75
80
85
90
95
100
0.1
1.0
10.0
100.0
1000.0
Vi=4.2V
Vi=3.6V
Vi=3.3V
Vi=2.0V
Vi=1.3V
5
Rev. 3/5/02,
*Patent Pending
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
Copyright 2002 Sipex Corporation
Figure 9. SP6641AEK-5.0 Line/Load Rejection Vs Load
Current
Figure 10. SP6641BEK-5.0 Line/Load Rejection Vs
Load Current
PERFORMANCE CHARACTERISTICS
Refer to the circuit in Figure 1, T
AMB
= +25
C
Figure 11. SP6641AEK-3.3 & SP6641AEK-5.0 No Load
Battery Current
Figure 12. SP6641BEK-3.3 & SP6641AEK-5.0 No Load
Battery Current
Figure 13. SP6641AEK-3.3 & SP6641AEK-5.0
Maximum Resistive Load Current in Startup
Figure 14. SP6641BEK-3.3 & SP6641BEK-5.0
Maximum Resistive Load Current in Startup
Iload (mA)
V
o
(V)
5.000
5.020
5.040
5.060
5.080
5.100
5.120
5.140
5.160
5.180
5.200
0
50
100
150
200
250
Vi=4.2V
Vi=3.6V
Vi=3.3V
Vi=2.0V
Vi=1.3V
Iload (mA)
V
o
(V)
4.900
4.920
4.940
4.960
4.980
5.000
5.020
5.040
5.060
5.080
5.100
0
200
400
600
800
Vi=4.2V
Vi=3.6V
Vi=3.3V
Vi=2.0V
Vi=1.3V
Vin (V)
Iin (uA)
0
50
100
150
200
250
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
SP6641AEK-5.0
SP6641AEK-3.3
Vin (V)
Iin (uA)
0
50
100
150
200
250
300
350
400
450
500
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
SP6641B-5.0
SP6641B-3.3
Vin (V)
Io (mA)
0
50
100
150
200
250
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
SP6641AEK-3.3, 22
H
SP6641AEK-3.3, 10
H
SP6641AEK-5.0, 22
H
SP6641AEK-5.0, 10
H
Vin (V)
Io (mA)
0
100
200
300
400
500
600
700
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
SP6641BEK-3.3, 22
H
SP6641BEK-3.3, 10
H
SP6641BEK-5.0, 22
H
SP6641BEK-5.0, 10
H
6
Rev. 3/5/02,
*Patent Pending
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
Copyright 2002 Sipex Corporation
I
OUT(MAX)
(
V
IN
) (
I
PK
K
OFF
)
V
OUT
2L
OPERATION
General Overview
The SP6641 is a high efficiency, low quiescent
current step-up DC-DC converter ideal for single
and dual cell alkaline and single cell Lithium Ion
battery applications such as medical monitors,
PDA's, MP3 players, and other portable end
products. The SP6641's 10
A quiescent cur-
rent, low 0.3
NFET switch, and unique PFM
control scheme combine to provide excellent
efficiency over a wide output power range.
Other features include a logic level enable con-
trol pin, guaranteed 0.9V startup, a tiny SOT23
5 pin package, and precise inductor peak current
control. SP6641A sources up to 90mA at 1.3V,
typ. and SP6641B sources up to 500mA at 2.6V,
typ. by supporting different peak inductor current
levels. Only two capacitors, an inductor, and a
diode are required to build a power supply for
the SP6641A. The SP6641B, 1A peak current
requires an additional small resistor and capaci-
tor as a low pass filter for the V
OUT
IC power pin.
Loop Regulation
The SP6641 combines a fixed inductor peak
current limit, a feed-forward minimum off-time
one-shot, and a precision loop comparator to
regulate the output voltage. Under light-load
conditions the loop operates as a standard PFM
converter. The frequency of fixed amplitude
inductor current triangles is modulated to regu-
late the load. Under heavy load conditions, the
converter adjusts the number of successive con-
tinuous mode current pulses to regulate the load.
Refer to the block diagram for the following
explanation of operating modes in loop regulation.
The output voltage is internally divided down and
fed to the negative terminal of the loop compara-
tor. A +1.25V bandgap reference voltage is ap-
plied to the positive terminal of the comparator. As
the output voltage droops below the regulation
threshold due to the load the loop comparator
output (signal V
OUT(LOW)
) transitions to a logic
"1". This sets the SR latch and initiates inductor
charging by pulling the signal NGATE high. In-
ductor charging continues until the current reaches
the internally programmed limit, at which point,
the off-time one-shot is triggered.
The off-time one-shot via signal T
OFF
resets the
SR latch regardless of the SET state (V
OUT(LOW)
),
opens the NMOS charge switch, and forces the
inductor to discharge through the rectifying
diode for a minimum time defined by the one-
shot duration. The end of the off-time pulse
releases the SR latch, and its output state is once
again determined by the output of the loop
comparator (V
OUT(LOW)
). Under light load con-
ditions, the output voltage will have been pulled
above the regulation threshold during the mini-
mum off-time, the signal V
OUT(LOW)
will be a
logic "0", and the NMOS charging switch will
remain open. The inductor current discharges
until it reaches zero or the loop comparator
triggers a new charge cycle.
Under a heavy load, the output voltage will
remain below the regulation point at the end of
the off-time pulse. In this condition, V
OUT(LOW)
has a logic value of 1 which immediately starts
a new charge/discharge cycle defined by the
peak inductor current and the minimum off-
time. The inductor current will remain in a
continuous conduction mode until the loop com-
parator indicates the output voltage is above the
regulation threshold, and the inductor current
will relax towards zero.
During continuous mode bursts, the inductor
current frequency and ripple amplitude are con-
trolled by the minimum off-time one-shot and
the input and output voltage levels. The SP6641
sets the minimum off-time to:
T
OFF
=
K
OFF
(V
OUT
V
IN
), where:
K
OFF
= Off-time Constant, typically 1.5
s*V
V
OUT
= Output Voltage
V
IN
= Input Voltage
Plugging the T
OFF
expression into the boost
mode equations yields the maximum output
current in regulation:
where:
= Efficiency, typically 0.80 to 0.90
I
PK
= Programmed inductor peak current, typi-
cally 0.33A for the SP6641A, typically
1.0A for the SP6641B.
L
= Inductor value
7
Rev. 3/5/02,
*Patent Pending
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
Copyright 2002 Sipex Corporation
The SP6641 feed forward off-time control de-
livers more load current than constant off-time
control because the input battery voltage drops
during its life cycle. The term (I
PK
K
OFF
/2L) is
the average current delivered to the output ca-
pacitor during the discharge phase. This is con-
stant with respect to input and output voltage.
With constant off-time control, the average dis-
charge current term becomes
(I
PK
-T
OFF
*(V
OUT
-V
IN
)/2L),
which decreases as the input voltage drops.
Table 1 illustrates the average inductor current
delivered to the load during discharge versus the
input voltage. The SP6641 feed forward off-
time control and the constant off-time control
are compared. For purposes of illustration, the
off times of each control scheme are normalized
at a typical two cell alkaline input voltage of
2.6V. The values used in Table 1 are:
I
PK
= 0.33A
L = 22
H
V
OUT
= 3.3V
T
OFF
(SP6641) = 1.5V*
s/(3.3-V
IN
)
T
OFF
(constant) = 2.14
s
SP6641A
Constant T
OFF
V
IN
T
OFF
Avg I
L
T
OFF
Avg I
L
3.0
5.00
s
0.30A
2.14
s
0.32A
2.6
2.14
s
0.30A
2.14
s
0.30A
2.0
1.15
s
0.30A
2.14
s
0.27A
1.3
0.75
s
0.30A
2.14
s
0.23A
1.0
0.65
s
0.30A
2.14
s
0.22A
Table 1- Average I
L
vs. Input Voltage
The following equation defines the burst mode
frequency under heavy load conditions:
where:
V
D
= Forward schottky drop, (0.4V, typ)
V
C
= Average charging switch drop,
Rnmos*I
PK
, typically 0.1V
Ignoring the conduction losses of V
D
and V
C
,
the burst frequency equation simplifies to:
F
BURST
=
(V
OUT
V
IN
)V
IN
K
OFF
V
OUT
Startup
The internal regulator circuitry is bootstrapped
to the V
OUT
pin. This requires a low voltage
oscillator and charging switch powered from the
V
BATT
pin to pump up the output voltage until
the reference is established. The reference pro-
vides a REFREADY signal that determines when
output control is handed over to the regulator.
REFREADY shuts down the startup circuit and
enables the regulator when the reference is valid
and V
OUT
is above +1.9V. Once the regulator is
given control it will continue to pump up the
output at full power until regulation is reached.
For two cell alkaline input voltages and above,
the output voltage will be pulled above +1.9V
quickly through the rectifying diode before the
reference has a chance to establish. In this sce-
nario the startup circuit will coarsely regulate
around +2.8V until the REFREADY signal as-
serts. This keeps the output from overshooting
in startup with higher input voltages.
Startup is guaranteed at +0.9V at room tempera-
ture with a 3k
load. Heavier loads will require
a higher input voltage.
Shutdown/Enable Control
Pin 4 of the device is a V
BATT
referred control
pin that shuts down the converter with the pin
tied to ground, or enables the converter with the
pin tied to V
BATT
. When the converter is shut-
down the power switch is opened and all circuit
biasing is extinguished leaving only junction leak-
age currents on supply pins 3 and 5. The output
voltage will droop to one diode drop below the
battery voltage through the rectifying diode.
After pin 4 is brought high, the startup circuit is
enabled and starts pumping up the output until
REFREADY hands over control to the internal
regulator.
OPERATION
Loop Regulation: continued
F
BURST
=
(
V
OUT
V
IN
) (
V
IN
V
C
)
K
OFF
V
OUT
+ V
D
V
C
8
Rev. 3/5/02,
*Patent Pending
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
Copyright 2002 Sipex Corporation
APPLICATION INFORMATION
Circuit Layout
Printed circuit board layout is a critical part of a
power supply design. Poor designs can result in
excessive EMI on the voltage gradients and
feedback paths on the ground planes with appli-
cations involving high switching frequencies
and large peak currents. Excessive EMI can
result in instability or regulation 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 inte-
grated into ground as a pseudo-ground plane.
On a multilayer PC board, route the star ground
using component-side copper fill, then connect
it to the internal ground plane using vias. For the
SP6641A/6641B devices, input and output fil-
ter capacitors should be soldered with their
ground pins as close together as possible in a
star-ground configuration. The VOUT pin must
be bypassed directly to ground as close to the
SP6641A/6641B devices as possible (within
0.2in or 5mm). The DC-DC converter and any
digital circuitry should be placed on the oppo-
site 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 VOUT node
and separated from it using grounded copper to
minimize EMI. See the SP6641A/6641B Evalu-
ation Board Manual for PC Board Layout de-
sign details.
Component Selection
Selection of capacitors, inductors and schottky
diodes for SP6641A and SP6641B power sup-
ply circuits can be made through the use of
Table 1 component selection. Capacitor equiva-
lent series resistance is a major contributor to
output ripple, usually greater than 60%. Low
ESR capacitors are recommended. Ceramic ca-
pacitors have the lowest ESR. Low-ESR tanta-
lum capacitors may be a more acceptable solu-
tion having both a low ESR and lower cost than
large ceramic capacitors. Designers should se-
lect input and output capacitors with a rating
exceeding the peak inductor current. Do not
allow tantalum capacitors to exceed their ripple-
current ratings. For example, in the SP6641A a
22
F, 6V, low-ESR, surface-mount tantalum
output filter capacitor typically provides 60mV
output ripple when stepping up from 1.3V to
3.3V at 20mA. An input filter capacitor can
reduce peak currents drawn from the battery and
improve efficiency. Low-ESR aluminum elec-
trolytic capacitors are acceptable in some appli-
cations but standard aluminum electrolytic ca-
pacitors are not recommended.
In selecting an inductor, the saturation current
specified for the inductor needs to be greater
then the SP6641A/B peak current to avoid satu-
rating the inductor, which would result in a loss
in efficiency and could damage the inductor.
The SP6641A evaluation board uses a Sumida
CDRH5D28 22
H inductor with an Isat value
of 0.9A and a DCR of 0.095
, which easily
handles the Ipeak of 0.33A of the SP6641A and
will deliver high efficiencies. The SP6641B
evaluation board uses a Sumida CDRH5D28
10
H inductor with an Isat value of 1.3A and a
DCR of 0.065
, which easily handles the Ipeak
of 1.0A of the SP6641B and will deliver high
efficiencies. Other inductors could be selected
provided their Isat is greater than the Ipeak of
the SP6641A/SP6641B.
Output Filter or LDO Regulator
Designers could add LC pi filters, linear post-
regulators, or shielding in applications necessary
to address excessive noise, voltage ripple, or EMI
concerns. The LC pi filter's cutoff frequency should
be at least a decade or two below the DC-DC
converters' switching frequency for the specified
load and input voltage. The SP6201, a small SOT23-
5pin 200mA Low Drop Out linear regulator can be
used at the SP6641A/6641B output to reduce
output noise and ripple. The schematic in figure 15
illustrates this circuit on the SP6641A Evaluation
Board with the SP6641 3.3V output followed by
the Sipex SP6201 3.0V output Low Drop Out
linear regulator.
9
Rev. 3/5/02,
*Patent Pending
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
Copyright 2002 Sipex Corporation
APPLICATION INFORMATION: continued
TABLE 1. COMPONENT SELECTION
INDUCTORS - SURFACE MOUNT
Inductor Specification
Sipex
Inductance
Manufacturer/
Series R
Isat
Size LxWxH
Inductor
Manufacturer
Part Number
(
H)
Part Number
(
)
(A)
(mm)
Type
Website
SP6641A Ipk = .33A
22
Sumida CDRH5D28-220
0.095
0.90
5.7x5.5x3
Shielded Ferrite Core
www.sumida.com
SP6641A Ipk = .33A
22
Coilcraft DO1608C-223
0.370
0.70
6.6x4.5x2.9
Unshielded Ferrite Core
www.coilcraft.com
SP6641A Ipk = .33A
22
TDK NLC453232T-220
0.900
0.37
4.4x3.2x3.2
Unshielded Ferrite Core
www.tdk.com
SP6641A Ipk = .33A
22
Murata LQH43C220K04
0.600
0.42
4.5x3.2x2.6
Unshielded Ferrite Core
www.murata.com
SP6641B Ipk = 1A
10
Sumida CDRH5D28-100
0.065
1.30
5.7x5.5x3
Shielded Ferrite Core
www.sumida.com
SP6641B Ipk = 1A
10
Coilcraft DO1608C-103
0.160
1.10
6.6x4.5x2.9
Unshielded Ferrite Core
www.coilcraft.com
SP6641B Ipk = 1A
10
Murata LQH55DN100M01
0.077
1.70
5x5x4.7
Unshielded Ferrite Core
www.murata.com
SP6641B Ipk = 1A
22
Sumida CDRH6D28-220
0.128
1.20
6.7x6.5x3
Shielded Ferrite Core
www.sumida.com
SP6641B Ipk = 1A
22
Murata LQH55DN220M01
0.160
1.20
5x5x4.7
Unshielded Ferrite Core
www.murata.com
CAPACITORS - SURFACE MOUNT & THRU-HOLE
Capacitor Specification
ESR
Ripple
Size
Sipex
Capacitance
Manufacturer/
(max)
Current
LxWxH
Voltage
Capacitor
Manufacturer
Part Number
(
F)
Part Number
(
)
@ 45
C (A)
(mm)
(V)
Type
Website
SP6641A Ipk = .33A
22
TDK C3225X5R0J226M 0.010
4.00
1210
6.3
SMT X5R Cer.
www.tdk.com
SP6641B Ipk = 1A
100
SANYO 10TPA100M
0.080
1.20
7343
6.3
SMT POSCAP Tant. www.sanyovideo.com
SP6641B Ipk = 1A
100
SANYO 16SA100M
0.030
2.70
8Dx10L
16.0
Thru-hole OS-CON
www.sanyovideo.com
SCHOTTKY DIODE - SURFACE MOUNT
Diode Specification
Sipex
Manufacturer/
VF @ IF
IF(AV)
Size LxWxH
Reverse V
Package
Manufacturer
Part Number
Part Number
(V)
(A)
(mm)
(V)
Type
Website
SP6641A Ipk = .33A
STMicro STPS0520Z
0.39
0.50
3.9x1.7x1.3
20
SOD-123
www.st.com
SP6641B Ipk = 1A
Zetex ZCHS2000
0.42
2.00
3x3x1.4
40
SOT23-6
www.zetex.com
Note: Components highlighted in bold are those used on the SP6641A or SP6641B Evaluation Board.
Maximum Startup Current
It should be noted that for low input voltages the
SP6641 startup circuit can not support large
load currents at startup. In startup the SP6641
needs to boost the output from zero volts using
a charge pump which has a limited current
capacity. Once the output is greater than 1.7 to
1.9V the operate circuit takes over and the
SP6641 can supply much more current. Curves
of maximum resistive load current in startup for
the SP6641A and SP6641B are shown in Fig-
ures 13 & 14 and can be compared with Figure
2, maximum load current in operation. Also,
Table 2 provides SP6641A 3.3V resistive load
current in startup for some low cost 1812 size
chip inductors.
From the curves in Figures 13 and 14, you can
see that for low input voltages, the 22
H induc-
tor has more current capacity at startup than the
10
H inductor, due to more energy per charge
cycle in the relationship
1
/
2
LI
2
. Thus for 1 cell
applications, 22
H is recommended for more
startup current than 10
H.
For 1-cell battery applications, it is recommended
to apply any large load current after the SP6641
has started up, typically in a few millisecs. This
is typically not a problem in many applications
where the load is a processor whose load current
is low until the processor voltage comes up.
10
Rev. 3/5/02,
*Patent Pending
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
Copyright 2002 Sipex Corporation
APPLICATION INFORMATION: continued
TABLE 2. SP6641A Resistive Load Current in Startup - low cost inductors
GND
LX
V
BATT
J1
L1
22
H
U1
SP6641
V
OUT
SHDN
C2
22
F
V
OUT
+3.3V
D1
1
2
3
C1
22
F
5
4
1
2
3
V
BATT
+0.9V to +3.3V Input
+
+
GND
ENABLE
V
OUT
SP6201
V
IN
RESET
1
2
3
5
4
V
OUT
+3.0V
C3
1
F
Figure 15. SP6641A 3.3V Evaluation Board with SP6201 LDO Regulator
SP6641A APPLICATION CIRCUIT WITH PANASONIC INDUCTOR
SP6641A APPLICATION CIRCUIT WITH TDK INDUCTOR
L1 = ELJ-PB220KF 22
H, IDCmax = 300mA, DCR = 1.0
L1 = NLC453232T-220K 22
H, IDCmax = 370mA, DCR = 0.9
Startup
V
OUT
I
OUT
Startup
Startup
V
OUT
I
OUT
Startup
Load
after
after
then
Load
after
after
then
V
IN
R
OUT
(min)
Startup
Startup
Load
V
IN
R
OUT
(min)
Startup
Startup
Load
V
V
mA
mA (max)
V
V
mA
mA (max)
0.86
16000
3.31
0.2
37
0.86
16000
3.30
0.2
42
0.88
1500
3.31
2
39
0.88
1500
3.30
2
43
0.90
800
3.30
4
40
0.90
900
3.30
4
44
0.95
230
3.30
14
44
0.95
260
3.30
13
48
1.00
125
3.30
26
48
1.00
126
3.30
26
52
1.10
73
3.29
45
56
1.10
66
3.29
50
60
1.20
58
3.29
57
63
1.20
49
3.29
67
69
1.30
50
3.28
66
71
1.30
43
3.29
77
77
1.40
43
3.28
76
78
1.40
39
3.29
84
84
1.50
39
3.28
84
86
1.50
36
3.29
91
91
SuperCap Application on the
SP6641 Output
When the battery input to SP6641A is removed,
the SP6641A output will end up in the charge
mode and will slowly discharge a Supercap
connected to the output. The typical Supercap
of 0.22F will go from fully charged at 3.3V to
less than 2V in 5 minutes. The following appli-
cation circuit in figure 16 is recommended to
disconnect the SP6641 output from the SuperCap
when the battery is removed. The small SOT23-
3pin MOS switches are an inexpensive addition
to the SP6641 circuit and work well to maintain
SuperCap voltage to retain Non-Volatile CMOS
Memory while a battery is changed.
11
Rev. 3/5/02,
*Patent Pending
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
Copyright 2002 Sipex Corporation
Low Battery Circuit for SP6641
Application
The circuit in figure 17 uses the Sipex SPX432
shunt regulator as a reference and comparator
circuit to detect a low battery condition and give
a high level, typically 1.7V output. When the
battery is good, the SPX432 output is low, but
not at ground but at 0.8V or about one Vbe
below the 1.24V reference. To translate that
level to a CMOS Low of less than 0.4V, an NPN
and 2 signal diodes can be added to the SPX432
Figure 17. SP6641A 3.3V with Low Battery Detection
APPLICATION INFORMATION: continued
output, as shown. The small SOT23-3pin
SPX432 and 2N3904 bipolar transistor and di-
odes are small and inexpensive to add to the
SP6641 circuit and work well to add a Battery
Low detection circuit, with the addition of about
130
A current from 3.3V out. As a bonus, the
output of this circuit can be used to drive the
SP6641 SHDN_N pin 3 to GND when the bat-
tery is removed, which would reset the SP6641
and eliminate the need for the SuperCap Switch
shown in figure 16.
GND
LX
V
BATT
L1
22
H
100k
U1
SP6641
V
OUT
SHDN
C2
22
F
R3
20k
Diode
Schottky
1
2
3
C1
22
F
5
4
V
BATT
R5
100k
BATT GOOD
D2
D3
1N4148
R2
100k
R1
44k
1N4148
V
OUT
3.3V
Q2
2N3904
2V = BATT GOOD
0V = LOW BATT
R4
1
2
3
REF
K
A
1.8V THRES. VTHRES = 1.24V(1 + R1/R2)
U2
SPX432M
SOT23-3
D1
GND
LX
V
BATT
SHDN
J1
L1
22
H
2.7V, 0.9
PMOS
SOT23-3 IRLML6302
Q1
U1
SP6641
V
OUT
SHDN
C2
22
F
V
OUT
+3.3V
Diode
Schottky
1
2
3
C1
22
F
5
4
1
2
3
V
BATT
C3
.22F Supercap
3.3V to
Nonvolatile Function
3
2
1
3
1
2
Q2 SOT23-3 IRLML2402
2.7V NMOS
R1
1M
Figure 16. SP6641A 3.3V with SuperCap Switch
12
Rev. 3/5/02,
*Patent Pending
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
Copyright 2002 Sipex Corporation
PACKAGE: 5 Lead SOT23
SYMBOL
A
A1
A2
b
C
D
E
E1
L
e
e1
a
1.45
0.15
1.30
0.50
0.20
3.10
3.00
1.75
0.55
10
O
0.90
0.00
0.90
0.25
0.09
2.80
2.60
1.50
0.35
0
O
MIN
MAX
0.95ref
1.90ref
E
A
e
C
L
b
e1
D
C
L
A2
A1
A
A
.10
C
L
E1
L
2
0.20
DATUM 'A
'
C
a
13
Rev. 3/5/02,
*Patent Pending
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
Copyright 2002 Sipex Corporation
ORDERING INFORMATION
Part Number
TOP MARK
Temperature Range
Package Type
SP6641AEK-3.3/TR ............. K1 ...................... -40
C to 85
C ........
(Tape & Reel) 5-Pin SOT-23
SP6641BEK-3.3/TR ............. L1 ...................... -40
C to 85
C ........
(Tape & Reel) 5-Pin SOT-23
SP6641AEK-5.0/TR ............. P1 ...................... -40
C to 85
C ........
(Tape & Reel) 5-Pin SOT-23
SP6641BEK-5.0/TR ............. Q1 ...................... -40
C to 85
C ........
(Tape & Reel) 5-Pin SOT-23
Corporation
SIGNAL PROCESSING EXCELLENCE
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.
Sipex Corporation
Headquarters and
Sales Office
22 Linnell Circle
Billerica, MA 01821
TEL: (978) 667-8700
FAX: (978) 670-9001
e-mail: sales@sipex.com
Sales Office
233 South Hillview Drive
Milpitas, CA 95035
TEL: (408) 934-7500
FAX: (408) 935-7600
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