ST SEA05 User Manual
Features
-
-
V
V
V
SEA05
Advanced constant voltage and constant current controller
■ Constant voltage and constant current control
■ Wide operating V
■ Low quiescent consumption: 200 µA
■ Voltage reference: 2.5 V
■ Voltage control loop accuracy +/- 0.5%
■ Current sense threshold: 50 mV
■ Open-drain output stage
■ Low external component count
■ SOT23-6L micro package
range [3.5 - 36] V
CC
Applications
■ Battery chargers
■ AC-DC adapters
■ LED drivers
Description
The SEA05 is a highly integrated solution for
SMPS applications requiring a dual control loop to
perform CV (constant voltage) and CC (constant
current) regulation.
The device integrates a voltage reference, two opamps (with OR-ed open-drain outputs), and a lowside current sensing circuit.
The voltage reference, along with one op-amp, is
the core of the voltage control loop; the current
sensing circuit and the other op-amp make up the
current control loop.
The external components needed to complete the
two control loops are: a resistor divider that
senses the output of the power supply and fixes
the voltage regulation setpoint at the specified
value; a sense resistor that feeds the current
sensing circuit with a voltage proportional to the
dc output current; this resistor determines the
current regulation setpoint and must be
SOT23 - 6L
adequately rated in terms of power dissipation;
the frequency compensation components (R-C
networks) for both loops.
The device, housed in one of the smallest
available package, is ideal for space-shrunk
applications such as adapters and chargers.
Figure 1. Internal schematic
cc
2.5
1.23 V
6
5
+
Out
ctrl
3
+
2
Gnd
14
Ictrl Isense
Table 1. Device summary
Order code Package Packing
SEA05TR SOT23-6L Tape and reel
April 2010 Doc ID 17014 Rev 1 1/10
www.st.com
10
Pin description SEA05
t
1 Pin description
Figure 2. Pin configuration
6
6
6
Isense
1
1
1
1
6
Vcc
GND
Vctrl
Note: The adjacent pins have the same AMR to increase the robustness of the IC against
accidental short circuit among pins.
Table 2. Pin description
n. Name Function
1 Isense
2GND
3Vctrl
4Ictrl
5OUT
Inverting input of the current loop op-amp. The pin is tied to the cold end of the
current sense resistor through a decoupling resistor.
Ground. Return of the bias current of the device. 0 V reference for all voltages.
The pin should be tied as close to the ground output terminal of the converter as
possible to minimize load current effect on the voltage regulation setpoint.
Inverting input of the voltage loop op-amp. The pin is tied to the mid-point of a
resistor divider that senses the output voltage.
Non-inverting input of the current loop op-amp. It is tied directly to the hot
(negative) end of the current sense resistor
Common open-drain output of the two internal op-amps. The pin, able to sink
current only, is connected to the branch of the optocoupler’s photodiode to
transmit the error signal to the primary side.
2
2
2
2
3
3
3
3
5
5
5
5
4
4
4
4
Ou
Ictrl
Supply Voltage of the device. A small bypass capacitor (0.1 µF typ.) to GND,
6Vcc
2/10 Doc ID 17014 Rev 1
located as close to IC’s pins as possible, might be useful to get a clean supply
voltage.
SEA05 Maximum ratings
V
Vo
-
-
V
V
o
R
2 Maximum ratings
Table 3. Absolute maximum ratings
Symbol Pin Parameter Value Unit
Vcc 6 Dc supply voltage -0.3 to 38 V
Vout 5 Open-drain voltage -0.3 to Vcc V
Iout 5 Max sink current 20 mA
Ictrl 4 Analog input -0.3 to Vcc V
Isense 1 Analog input -0.3 to 3.3 V
Vctrl 3 Analog input -0.3 to 3.3 V
Table 4. Thermal data
Symbol Parameter Value Unit
R
Tj
T
Thermal resistance, junction-to-ambient 250 °C/W
thJA
Junction temperature operating range -40 to 150
op
Storage temperature -55 to 150
STG
3 Typical application schematic
Figure 3. Typical application schematic
0.1μF
cc
2.5 V
-50 mV
1.23
+
0 V
+
Ictrl Isense
5
3
2
14
°C
R1
Out
Vctrl
Gnd
R2
csth
Rsense
I
O 5.2*
V
=
21
RR
+
2
V
O
max =
VI05.0
sense
R
Doc ID 17014 Rev 1 3/10
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