SP6641A SIPEX [Sipex Corporation], SP6641A Datasheet - Page 10

• Manufacturer Part Number: SP6641A
• Description: 500mA Alkaline DC/DC Boost Regulator in SOT-23
• Manufacturer: SIPEX [Sipex Corporation]

APPLICATION INFORMATION: continued
Figure 15. SP6641A 3.3V Evaluation Board with SP6201 LDO Regulator
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-
TABLE 2. SP6641A Resistive Load Current in Startup - low cost inductors
Rev. 3/5/02, *Patent Pending
SP6641A APPLICATION CIRCUIT WITH PANASONIC INDUCTOR
0.86
0.88
0.90
0.95
1.00
1.10
1.20
1.30
1.40
1.50
L1 = ELJ-PB220KF 22 H, IDCmax = 300mA, DCR = 1.0
V
V
IN
D1
+0.9V to +3.3V Input
R
OUT
16000
Startup
1500
V
Load
800
230
125
BATT
73
58
50
43
39
22 F
(min)
C2
+
1
2
3
Startup
3.31
3.31
3.30
3.30
3.30
3.29
3.29
3.28
3.28
3.28
V
after
LX
GND
V
OUT
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
V
OUT
22 H
SP6641
L1
U1
SHDN
V
Startup
®
®
BATT
after
I
0.2
mA
14
26
45
57
66
76
84
22 F
OUT
2
4
C1
5
4
+
1
2
3
mA (max)
Startup
Load
then
37
39
40
44
48
56
63
71
78
86
J1
10
L1 = NLC453232T-220K 22 H, IDCmax = 370mA, DCR = 0.9
V
+3.3V
OUT
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.
0.86
0.88
0.90
0.95
1.00
1.10
1.20
1.30
1.40
1.50
SP6641A APPLICATION CIRCUIT WITH TDK INDUCTOR
V
V
IN
R
OUT
16000
Startup
1500
Load
900
260
126
1
2
3
66
49
43
39
36
(min)
ENABLE
V
GND
IN
SP6201
Startup
3.30
3.30
3.30
3.30
3.30
3.29
3.29
3.29
3.29
3.29
V
after
OUT
V
© Copyright 2002 Sipex Corporation
RESET
®
®
V
OUT
Startup
5
4
after
I
0.2
mA
13
26
50
67
77
84
91
OUT
2
4
V
+3.0V
mA (max)
OUT
C3
1 F
Startup
Load
then
42
43
44
48
52
60
69
77
84
91