POWER MANAGEMENT
1www.semtech.com
SC1410A
Constant Voltage/Constant Current
Battery Charger
Features
Applications
Revision: September 14, 2005
Typical Application Circuits
Description
The SC1410A is designed to provide a simple, fast charg-
ing solution for rechargeable batteries that require con-
stant-current and/or constant voltage charging, including
nickel-cadmium (NiCd), nickel-metal-hydride (NiMH) and
lithium-ion (Li-Ion). With a voltage reference accuracy of
0.5% the SC1410A satisfies the tight constant-voltage
charging requirements of lithium cells.
The SC1410A simplifies battery charger design by inte-
grating a high efficiency PWM with an internal 1.5A switch
and 0.1ohm current sense resistor, while the 500kHz
switching frequency allows a very small inductor to be used.
Only one external resistor is required to program the full
1.5A charging current to within 5% accuracy.
Charging circuits for batteries ranging from 2V to 18V are
easily implemented using the SC1410A. No ground sens-
ing of current is required, allowing the battery’s negative
terminal to be connected directly to ground. No blocking
diode is required between the IC and the battery since the
SC1410A enters sleep mode and consumes only 3µA when
the AC adapter is unplugged. Other features include soft
start, overvoltage protection, and a shutdown pin. The
SC1410A is available in a 16 pin QSOP package.
Charges NiCd, NiMH and Lithium-lon batteries
High efficiency current mode with 1.5A internal
switch and sense resistor
3% Typical charging current accuracy
Precision 0.5% voltage reference for voltage mode
charging or over voltage protection
Current sensing can be either terminal of battery
Low reverse battery drain current: 3µA
Charging current soft start
Shutdown control
500kHz switching uses small inductor
Chargers for NiCd*, NiMH* and Lithium batteries
Step down switching regulator with precision
adjustable current limit
*NiCd and NiMh batteries require external charge termi-
nation circuitry not contained in the SC1410A
Figure 2: Charging Lithium batteries
6.19k
22uF
Cout
1k
11 to 18V
+
4.2V
+
4.2V
1N4148
1N5819
240k
0.25%
SC1410A
SW VCC
VC
PROG
SENSE
BOOST
BAT
GND
OVP
300
1410 SCH42
1uF
0.22uF
33uH
0.1uF
1N5819
100k
0.25%
NDS355N
10uF
Cin
Figure 1: 500kHz Li-lon cell phone charger
8.2 to 18V
NDS355N
70.6k
0.25%
6.19k
+
4.2V
SC1410A
SW VCC
VC
PROG
SENSE
BOOST
BAT
GND
OVP
10uF
Cin 1N5819
1k
10uH
1uF
1410 SCH41
22uF
Cout
300
1N5819
1N4148
100k
0.25%
0.22uF
0.1uF
22005 Semtech Corp. www.semtech.com
POWER MANAGEMENT
SC1410A
Electrical Characteristics
Absolute Maximum Ratings
retemaraPlobmySmumixaMstinU
egatloVylppuSV
)XAM(CCV
02V
DNGottcepserhtiwegatloVhctiwS 3-V
DNGottcepserhtiwegatloVniPtsooB 5-/42+V
egatloVniPPVO,GORP,CV 8V
I
TAB
)egarevA( 5.1A
esaCotnoitcnuJ,ecnatsiseRlamrehT θ
CJ
03W/C°
tneibmAotnoitcnuJ,ecnatsiseRlamrehT θ
AJ
57W/C°
egnaRerutarepmeTgnitarepOT
A
07ot0C°
egnaRerutarepmeTegarotST
GTS
051+ot56-C°
.ceS01)gniredloS(erutarepmeTdaeLT
DAEL
003C°
Unless specified: VVCC = 16V, VBAT = 8V, IBAT=0
retemaraPsnoitidnoCniMpyTxaMstinU
tnerruCylppuSV
GORP
V,V7.2=
CCV
≤V025.45.6Am
I,tnerruCyrettaBCD
TAB
V<V8
CCV
V<V0,V81<
TAB
≤V61
R
GORP
k39.4=
R
GORP
k82.3=
R
GORP
k3.94=
39.0
53.1
57
0.1
5.1
001
70.1
56.1
521
A
A
Am
egatloVgnitarepOtupnImuminiMtuokcolegatlovrednU2.67 8.7V
yrettaBmorftnerruCesreveRV
TAB
≤C°0,V21 ≤T
J
≤C°07302Aµ
tnerruCniPtsooBV
CCV
V-
TSOOB
≤V81
V2 ≤V
TSOOB
V-
CCV
≤)NOhctiwS(V61
52.0
6
03
41
Aµ
Am
hctiwS
ecnatsiseRNOhctiwSV
CCV
V01=
I
WS
V.A5.1=
TSOOB
V-
WS
≥V2
I
WS
V,A1=
TSOOB
V-
WS
V2<
5.056.0
0.2
Ω
∆I
TSOOB
/∆I
WS
NOhctiwSgniruD V
TSOOB
I,V42=
WS
≤A10253A/Am
tnerruCegakaeLFFOhctiwSV
WS
V,V0=
CCV
≤V814002 µA
VmumixaM
TAB
NOhctiwShtiw V
CCV
2-V
ImuminiM
GORP
NOhctiwSrof 402µA
ImuminiM
GORP
FFOhctiwSrofV
GORP
≤V15.04.2Am
Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified
in the Electrical Characteristics section is not implied.
3
2005 Semtech Corp. www.semtech.com
POWER MANAGEMENT
SC1410A
Electrical Characteristics (Cont.)
Unless specified: VVCC = 16V, VBAT = 8V, IBAT=0
retemaraPsnoitidnoCniMpyTxaMstinU
)TAB,ESNES(stupnIreifilmAesneStnerruC
)1SR(ecnatsiseResneS 80.021.0 Ω
TABotESNESmorfecnatsiseRlatoT 2.052.0 Ω
tnerruCsaiBTABV
CV
V3.0<
V
CV
V6.0>
002-
007
573-
0031
Aµ
)woL(timiLedoMnommoCtupnI 52.0-V
)hgiH(timiLedoMnommoCtupnI V
CCV
2-V
ecnerefeR
egatloVecnerefeRR
GORP
htiwPVOtaderusaeM,k82.3=
IgniylppusAV
GORP
FFOhctiwSdna
844.2564.2284.2V
ecnareloTegatloVecnerefeRV8≤V
CCV
≤C°0,V81 ≤T
J
≤C°07
V8 ≤V
CCV
≤C°0,V81 ≤T
J
≤C°521
644.2
144.2
564.2084.2
984.2
V
rotallicsO
ycneuqerFgnihctiwS 044005055zHk
elcyCytuDmumixaM 77%
)2AC(reifilpmAtnerruC
ecnatcudnocsnarTV
CV
I,V1=
CV
Aµ1±=051052055ohmµ
VmumixaM
CV
FFOhctiwSrof 6.0V
I
CV
)niPfotuO(tnerruCV
CV
≥V6.0001Aµ
)AV(reifilpmAegatloV
ecnatcudnocsnarT Aµ005otAµ001morftnerructuptuO5.02.15.2ohm
V,tnerruCecruoStuptuO
CCV
V01=V
GORP
V=
PVO
V=
FER
Vm03+3.1Am
tnerruCsaiBtupnIPVO tnerruCtuptuOAVAm57.0tA05051An
42005 Semtech Corp. www.semtech.com
POWER MANAGEMENT
SC1410A
Pin Configuration Ordering Information
Pin Descriptions
Notes:
(1) Only available in tape and reel packaging. A reel
contains 2500 devices.
(2) Lead free product. This product is fully WEEE and
RoHS compliant.
eciveDegakcaP
)1(
RT.SQCA0141CS
61-POSQ
TRTSQCA0141CS
)2(
rebmuNniPemaNniPnoitcnuFniP
61,9,8,1DNG ecnamrofreplamrehtmumitporofelddaphcattaeidehtotdesuferasniPdnuorGesehT
.aerareppocBCPegralotsnipesehttcennoc
2WS.tuptuohctiwS
3TSOOB egatlov-nowolaotrotsisnartNPNrewophctiwsehtevirddnapartstoobotdesusinipsihT
.noitapissidrewopwolrof
4DNG.nipdnuorG
5PVO .deriuqertonfidnuorg,tuptuoegatlovtnatsnocrofedonkcabdeeF
11,6CN.snipesehtottcennoctonod,noitcennocoN
7ESNES .yrettabehtfolanimretrehtietaebnacgnisneS.tupni1ACreifilpmatnerruC
01TAB.tupni1ACreifilpmatnerruC
21CV dnaV7.0tastratsgnihctiwS.MWPedomtnerrucehtfopoolretniehtfolangislortnoC
taforoticapacA.noitarepolamronnitnerrucgnigrahcrehgihotsdnopserrocCVrehgih
,gnihctiwsnwodtuhsoT.tratstfosfoetarehtslortnocdnaesiontuosretlifDNGotfu1tsael
.Au03sitnerructuptuolacipyT.wolnipsihtllup
31GORP .noitasnepmocpoolmetsysrofdnatnerrucgnigrahcehtgnimmargorprofsinipsihT
411CCV.pihcehtrofylppuS
512CCV.pihcehtrofylppuS
1
2
3
4
5
6
7
8
GNDGND
TOP VIEW
(16 Pin QSOP)
13
12
14
15
16
11
10
9
VCC2SW
VCC1BOOST
PROGGND
VCOVP
NCNC
BATSENSE
GNDGND
5
2005 Semtech Corp. www.semtech.com
POWER MANAGEMENT
SC1410A
Block Diagram
1k
VBAT
VC
VSW
+
-
SLOPE
COMP.
SW
IPROG
IBAT
+
-
SHUTDOWN
QSW
SENSE
60k
VREF
2.465V
+
-
CA1
BOOST
500kHz
OSCILLATOR
+
-
CA2
R
S
Q
BAT
0.7V
VCC
+
-
+
-
VA
RS1
+
-
PROG
1410 SCH22
VCC
= 500uA/A
OVP
IPROG
R
PROG
C
PROG
Theory of Operation
The SC1410A is a current mode, buck converter which
operates in constant current (CC) and constant voltage
(CV) modes. There are two feedback mechanisms, a frac-
tion of the output voltage is sensed at OVP and the out-
put current is sensed by RS1. When either or both of
these feedback mechanisms are implemented, the loops
act to maintain a nearly constant voltage of VREF at the
PROG pin.
In CC mode, the current amplifier CA1 and the sense resis-
tor RS1 combine to generate a program current (IPROG) to
output current ratio of 500µA/A. The programmed output
current is therefore given by :-
Ω
=
⋅
=⋅=
k in R Amps, in is I
where
I
93.4
R
or
R
465.22
I2000I
PROGBAT
BAT
PROG
PROG
PROGBAT
As the voltage at the OVP pin rises, reaching VREF, the
voltage amplifier VA sources current into RPROG, reducing
IBAT. IBAT will go from full programmed current to zero with
only a few mV increase at the OVP pin.
The SR latch is set by the 500kHz oscillator, turning on
the output transistor (QSW). The outer control loop of CA2,
the 60k resistor and external components on the VC pin
sets a DC level against which the inner loop DC and AC
current information generated by RS1, CA1 and the buffer
and divider is compared. When the voltage at the + pin of
the comparator exceeds the DC level at the - pin, the latch
is reset and QSW turned off.
62005 Semtech Corp. www.semtech.com
POWER MANAGEMENT
SC1410A
Component Selection
Inductor - A suitable value of inductor for most applica-
tions is 10uH, this value is a compromise between ripple
current and size. A 10uH inductor will result in less than
1A pk. pk. ripple at maximum input voltage and 50% duty
cycle, which is the worst case. Higher inductance values
will result in lower ripple but for similar current ratings, will
be physically larger and more costly. The inductor should
be sized so that it will not saturate at peak current. Peak
inductor current is:-
()
2
VV
fLV
V
II OIN
IN
O
OPK −
⋅
⋅⋅
+=
Input and Output capacitors - There are no special re-
quirements for input and output capacitors beyond the
capability to handle the ripple current. For the input
capacitor(s) the RMS ripple current rating required is ap-
proximately 50% of IBAT and for the output capacitor(s) the
worst case RMS ripple rating required can be determine
from:-
()
32
VV
fLV
V
IOIN
IN
O
RMS ⋅−
⋅
⋅⋅
=
Note that this ripple rating is not a function of IBAT. Worst
case ripple current rating requirement occurs at VO=VIN/2.
Good choices for input and output capacitors are high value
ceramics, special polymer capacitors such as those from
Panasonic or, if space permits, low ESR aluminum
electrolytics. Tantalum capacitors are not recommended,
particularly for input capacitors unless they are specially
tested for surge current and heavily derated for voltage.
RPROG - The current programming resistor determines the
charging current according to the following equations:-
Ω
=
⋅
=⋅=
k in R Amps, in is I
where
I
93.4
R
or
R
465.22
I2000I
PROGBAT
BAT
PROG
PROG
PROGBAT
Soft Start - A capacitor on the VC Pin implements the
soft start function for the SC1410A. Soft start controls
the rate at which output voltage rises so that high cur-
rent surges can be avoided or minimized. In order for
soft start to be effective, the soft start time must be
much longer than the ramp up time of the input supply.
The ratio of the soft start cap to the PROG pin cap must
also be chosen to ensure that the PROG pin does not lag
the soft start. Recommended values for the soft start
capacitor and the PROG pin capacitor are 1uF and 0.1uF
respectively. The input supply must also be specified with
some care. It is possible for a current limited or power
limited input supply to “latch-up” and operate at a lower
output voltage than it is designed for, be sure that the
supply can provide adequate power at the UVLO point.
For example, charging a battery at 800mA with a 3.6V
terminal voltage (typical for a partially discharged single
cell Li-Ion) requires 3.6*0.8=2.88W, allowing for effi-
ciency one might choose a 3.6W Input supply or 300mA
at 12V. However if the 300mA is a hard current limit, as
the supply ramps up through the SC1410A UVLO at 7V,
the available output power is only 7*0.3 or 2.1W. If soft
start is too fast or the input supply ramp up is too slow,
the input supply will become “stuck” at this low level and
will oscillate around the 1410A UVLO point. To prevent
this from happening, choose a higher power input supply
or ensure soft start timings are adequate or use an ex-
ternal UVLO, holding down the VC pin until the input sup-
ply has ramped to a voltage where it can sustain the
required output power.
7
2005 Semtech Corp. www.semtech.com
POWER MANAGEMENT
SC1410A
Efficiency at 4.2V output
12V
Vin=18V
8V
60%
70%
80%
90%
100%
0.0 0.2 0.4 0.6 0.8 1.0
Io (A)
Efficiency (%)
Vout=4.2V
Input diode
losses included
Efficiency at 8.4V output
12V
Vin=15V
60%
70%
80%
90%
100%
0.0 0.2 0.4 0.6 0.8 1.0
Io (A)
Efficiency (%)
Vout=8.4V
Input diode
losses included
VC Pin characteristics
-200
-150
-100
-50
0
0.0 0.5 1.0 1.5 2.0
VVC (V)
IVC (µA)
Typical Characteristics
82005 Semtech Corp. www.semtech.com
POWER MANAGEMENT
SC1410A
Outline Drawing - QSOP-16
SEE DETAIL DETAIL A
A
.025 BSC
.236 BSC
16
.007
.150
.189
.154
.193
.008 -
16
0.18
0.635 BSC
6.00 BSC
3.90
4.90
-
.158
.197
3.80
4.80
.012 0.20
4.00
5.00
0.31
bxN
2X N/2 TIPS
SEATING
aaa C
E/2
2X
12
N
A
D
A1
EE1
bbb C A-B D
ccc C
A2
(.041)
.004
.008
-
.033
-
-
-
-
0°
.016
.006
.049
.004
.053
8° 0°
0.20
0.10
-8°
0.40
0.15
1.25
0.10
.041
.010
.069
.065
.010
1.35
(1.04)
0.84
-
1.04
0.25
-
-
-1.75
1.65
0.25
0.25
-
.010 .020 0.50
-
c
L
(L1) 01
0.010
GAGE
PLANE
H
3
h
h
A
eD
e/2
B
C
PLANE
3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS
OR GATE BURRS.
-B-
CONTROLLING DIMENSIONS ARE IN INCHES (ANGLES IN DEGREES).
DATUMS AND TO BE DETERMINED AT DATUM PLANE
NOTES:
1.
2. -A- -H-
SIDE VIEW
INCHES
DIMENSIONS
NOM
L1
N
01
bbb
aaa
ccc
A
A2
A1
D
E
E1
DIM
c
h
L
e
MIN
b
MAX
MILLIMETERS
MINMAX NOM
REFERENCE JEDEC STD MO-137, VARIATION AB.
4.
9
2005 Semtech Corp. www.semtech.com
POWER MANAGEMENT
SC1410A
P
X
(C)
Y
Z
G
.268
.072
.016
.025
(.195)
.123
(4.96)
6.80
1.84
0.40
0.635
3.12
INCHES
DIMENSIONS
Z
P
Y
X
DIM
C
G
MILLIMETERS
THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
NOTES:
1.
Land Pattern - QSOP-16
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