Description
SE1052 is a highly integrated solution for SMPS
applications requiring CV (constant voltage) and CC
(constant current) modes. It also has built-in LED
drivers specifically designed for stand-alone Battery
Charging applications. SE1052 integrates three
voltage references, three operational amplifiers, and
two current sensing circuits together in the same IC.
The
1
st
voltage
reference,
together
with
one
operational amplifier, controls the output voltage.
The 2
nd
voltage reference, together with another
operational amplifier, senses and limits the amount of
the current on the low side, hence the overall current
at the output. The 3
rd
voltage reference and
operational amplifier senses when the charging
current drops to 10% of the programmed value.
During charging, SE1052 will turn on Red LED. When
the charging is completed, SE1052 will turn on Green
LED. The SE1052 is available in SOP8 and DIP8
package.
Features
Constant Voltage and Constant Current Control
Low Voltage Operation
Precision Internal Voltage References
Low External Component Count
Current Sink Output Stage
Easy Compensation
Low AC Mains Voltage Rejection
Rugged 1.5KV ESD withstand capability.
Internal 2 LED drivers
Available in SOP8 and DIP-8 Package.
RoHS Compliant and 100% Lead (Pb)-Free
Application
Adapters
Digital Camera Chargers.
Cellphone Chargers.
Other Battery Chargers
Ordering Information
Device
Package
SOP8 and
V
OUT
Fixed output voltages
1.21V
Pin Configuration
SOP8 T View
op
Green
Output
GND
Vctrl
1
2
3
4
8
7
6
5
Red
Ictrl
Vsense Output
Vcc
GND
Vctrl
3
4
6
5
Vsense
Vcc
2
7
Ictrl
Green
DIP8 Top View
1
8
Red
SE1052
DIP8
(Lead-free)
Pin Description
Name
Green
V
OUT
GND
V
CTRL
V
CC
V
SENSE
I
CTRL
Red
Pin#
1
2
3
4
5
6
7
8
Type
Driver
Current Sink Output
Power Supply
Analog Input
Power Supply
Analog Input
Analog Input
Driver
Function
Turning on Green LED when the charging is completed.
Output Pin. Sinking Current Only
Ground Line. 0V Reference For All Voltages
Input Pin of the Voltage Control Loop
Positive Power Supply Line
Input Pin of the Current Control Loop
Input Pin of the Current Control Loop
Turning on Red LED when the charging is in progress.
Revision 5/7/2009
Preliminary and all contents are subject to change without prior notice.
© Seaward Electronics, Inc., 2006. • www.seawardinc.com.cn • Page 1
Absolute Maximum Rating
Symbol
V
CC
V
IN
θ
JA
T
J
T
STG
T
LEAD
DC Supply Voltage
Input Supply Voltage
Thermal Resistance Junction to Ambient
Operating Junction Temperature Range
Storage Temperature Range
Lead Temperature (Soldering 10 Sec)
Parameter
Maximum
18
-0.3~ V
CC
250
0 to 125
-40 to 150
260
Units
V
V
°C/W
°C
°C
°C
Electrical Characteristic
V
CC
= 5.0V, T
A
= 25°C, unless otherwise specified.
Symbol
Parameter
Conditions
Total Current Comsuption
I
CC
Total Supply Current - not taking the output sinking
current into account
ISINK=0
0.7
1.2
2.5
mA
Min
Typ
Max
Unit
Voltage Control Loop
G
mv
V
REF
LR
V
I
IBV
V
OL
I
OS
Transconduction Gain (Vctrl). Sink Current Only
1
）
Voltage Control Loop Reference
2
）
Linear Regulation of Voltage Control Loop
Reference
Input Bias Current (Vctrl)
Low Output Voltage at 10mA Sinking Current
Output Short Circuit Current. Output to VCC. Sink
Current Only
Vctrl=Vcc, Ictrl=Vsense=GND,
ISINK=10mA, G and R Pins Open
Vctrl=Vout=Vcc, Ictrl=Vsense=GND,
G and R Pins Open
Current Control loop
G
mi
V
SENSE
LR
I
I
IBI
V
OL
I
OS
Transconduction Gain (Ictrl). Sink Current Only
3
）
Current Control Loop Reference
4
）
Linear Regulation of Current Control Loop
Reference
Current out of pin Ictrl at -200mV
Low Output Voltage at 10mA Sinking Current
Output Short Circuit Current. Output to VCC. Sink
Current Only
Vsense=Vcc, Ictrl=Vctrl=GND,
ISINK=10mA, G and R Pins Open
Vsense=Vout=Vcc, Ictrl=Vctrl=GND,
G and R Pins Open
15
ISINK=0 to 5mA
ISINK=0
Vcc=2.5V to 18V
192
7.2
200
0.8
20
250
24
350
35
208
4
mA/mV
mV
mV
uA
mV
mA
15
ISINK=0 to 10mA
ISINK=0
Vcc= 2.5V to 18V
1.198
2.4
1.21
0.6
70
250
24
350
35
1.222
8
mA/mV
V
mV
nA
mV
mA
Revision 5/7/2009
Preliminary and all contents are subject to change without prior notice.
© Seaward Electronics, Inc., 2006. • www.seawardinc.com.cn • Page 2
Electrical Characteristic
V
CC
= 5.0V, T
A
= 25°C, unless otherwise specified.
Symbol
Current Monitor Loop
V
TH
H
ys
Threshold Voltage of Turning Red Pin from Low to High
Hysterisis of the comparator in Current Monitor Loop
20
14
mV
mV
Parameter
Conditions
Min
Typ
Max
Unit
1. If the voltage on V
CTRL
(the negative input of the amplifier) is higher than the positive amplifier input
(V
REF
=1.210V), and it is increased by 1mV, the sinking current at the output OUT will be increased by 2.4mA.
2. The internal Voltage Reference is set at 1.210V. The internal Voltage Reference is fixed by bandgap, and
trimmed to 1% accuracy at room temperature.
3. When the positive input at I
CTRL
is lower than -200mV, and the voltage is decreased by 1mV, the sinking current
at the output OUT will be increased by 2.9mA.
4. The internal current sense threshold is set to -200mV. The current control loop precision takes into account the
cumulative effects of the internal voltage reference deviation as well as the input offset voltage of the
trans-conduction operational amplifier.
Revision 5/7/2009
Preliminary and all contents are subject to change without prior notice.
© Seaward Electronics, Inc., 2006. • www.seawardinc.com.cn • Page 3
Typical Application
Rs
To primary
Vout+
R2
SE1052
1.210V
Vcc
Output
Rout
C2
22 pF
Rvc1
Cs
100mV
Cvc1
2.2nF
Rled
1K
R1
Vctrl
Cic1
2.2nF
Ric1
10mV
Red
Ictrl
Vsense
GND
Ric2
Rsense
Green
LED_R LED_G
Vout-
Note：0 ohms of Ric2 is recommended for LED charging indication function.
Revision 5/7/2009
Preliminary and all contents are subject to change without prior notice.
© Seaward Electronics, Inc., 2006. • www.seawardinc.com.cn • Page 4
Application Hints
Voltage Control
The voltage loop is controlled via a first
transconductance operational amplifier, the
resistor bridge R1, R2, and the optocoupler which
is directly connected to the output.
The relation between the values of R1 and R2
should be chosen as written in Equation 1.
R1 = R2 x Vref / (Vout - Vref)
Eq1
The current sinking outputs of the two
trans-conductance operational amplifiers are
connected together. This makes an ORing function
which ensures that whenever the current or the
voltage reaches too high values, the optocoupler is
activated.
The relation between the controlled current and the
controlled output voltage can be described with a
square characteristic as shown in the following V/I
output-power graph.
Where Vout is the desired output voltage. To
avoid the discharge of the load, the resistor bridge
R1, R2 should be highly resistive. For this type of
application, a total value of 100KΩ (or more)
would be appropriate for the resistors R1 and R2.
As an example, with R2 = 100KΩ, Vout = 4.10V,
Vref = 1.210V, then R1 = 41.9KΩ.
Note that if the low drop diode should be inserted
between the load and the voltage regulation
resistor bridge to avoid current flowing from the
load through the resistor bridge, this drop should
be taken into account in the above calculations by
replacing Vout by (Vout + Vdrop).
Current Control
The current loop is controlled via the second
trans-conductance operational amplifier, the
sense resistor Rsense, and the optocoupler.
The control equation is:
Rsense x I-limit = Vsense
Eq2
Rsense = Vsense / I-limit
Eq3
where I-limit is the desired current limit, and
Vsense is the threshold voltage for the current
control loop.
As an example, with I-limit = 1A, Vsense =
-200mV, then Rsense = 200mΩ.
Note that the Rsense resistor should be selected
with the consideration of the Maximum Power in
full load operations (P-limit).
P-limit = Vsense x I-limit.
Eq4
As an example, with I-limit = 1A, and Vsense
=-200mV, P-limit = 200mW.
Consequently, for most adapter and battery
charger applications, a quarter-watt resistor to
make the current sensing function is sufficient.
Vsense threshold is achieved internally by a
resistor bridge tied to the Vref voltage reference.
Its middle point is tied to the positive input of the
current control operational amplifier, and its foot is
to be connected to lower potential point of the
sense resistor as shown on the following figure.
The resistors of this bridge are matched in layout
to provide the best precision possible.
Revision 5/7/2009
Fig.2 Output voltage versus output current
Compensation
The voltage-control trans-conductance operational
amplifier can be fully compensated. Both of its
output and negative input are directly accessible for
external compensation components.
An example of a suitable compensation network is
shown in Fig.1. It consists of a capacitor
Cvc1=2.2nF and a resistor Rcv1=470KΩ in series,
connected in parallel with another capacitor
Cvc2=22pF.
The current-control trans-conductance operational
amplifier can also be fully compensated. Both of its
output and negative input are directly accessible for
external compensation components.
An example of a suitable compensation network is
shown in Fig.1. It consists of a capacitor
Cic1=2.2nF and a resistor Ric1=22KΩ in series.
When the Vcc voltage reaches 12V it could be
interesting to limit the current coming through the
output in the aim to reduce the dissipation of the
device and increase the stability performances of
the whole application.
An example of a suitable Rout value could be
330Ω in series with the opto-coupler in case
Vcc=12V.
Driving LED
SE1052 provides direct driving pins to Red and
Green LED’s for charging applications. During
charging, SE1052 will turn on Red LED. When the
charging is completed, SE1052 will turn on Green
LED.
Preliminary and all contents are subject to change without prior notice.
© Seaward Electronics, Inc., 2006. • www.seawardinc.com.cn • Page 5
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