UNISONIC TECHNOLOGIES CO., LTD
L2800
SWITCHING REGULATOR
CONTROLLER(LOW VOLTAGE)
DESCRIPTION
SOP-8
LINEAR INTEGRATED CIRCUIT
The UTC
L2800
which is incorporating a soft start function and
short circuit detection function is a single-channel switching
regulator control IC and is made for low voltage applications.
Because the device has a low minimum operating voltage of 1.8V,
so it is ideal for the power supply of battery-operated electronic
equipment.
TSSOP-8
FEATURES
*Wide supply voltage operating range: 1.8V~15V
*Low current consumption: Typically 5.5mA in operation,1μA or
less in stand-by
*High speed operation is possible: Maximum 1MHz
*The error amplifier gain is set inside the IC, so peripheral
components are minimized.
*Incorporates a soft start circuit.
*Incorporates a timer-latch type short circuit detection circuit (SCP).
*Totem-pole type output with adjustable on/off current (for NPN
transistors)
*Incorporates a stand-by function.
ORDERING INFORMATION
Ordering Number
Lead Free
Halogen Free
L2800L-S08-T
L2800G-S08-T
L2800L-S08-R
L2800G-S08-R
L2800L-P08-T
L2800G-P08-T
L2800L-P08-R
L2800G-P08-R
Package
SOP-8
SOP-8
TSSOP-8
TSSOP-8
Packing
Tube
Tape Reel
Tube
Tape Reel
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QW-R103-030.C
L2800
PIN CONFIGURATION
LINEAR INTEGRATED CIRCUIT
PIN DESCRIPTION
SYMBOL
-IN
SCP
VCC
BR/CTL
OUT
GND
OSC
FB
I/O
I
-
-
I
O
-
-
O
DESCRIPTION
Error amplifier inverting input pin
Soft start and SCP setting capacitor connection pin
Power supply pin
Output current setting and control pin
Totem-pole type output pin
Ground pin
Capacitor and resistor connection pin for setting the oscillation frequency
Error amplifier output pin
PIN NO.
1
2
3
4
5
6
7
8
BLOCK DIAGRAM
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QW-R103-030.C
L2800
ABSOLUTE MAXIMUM RATINGS
(T
A
=25C)
SYMBOL
V
CC
I
O+
I
O-
PARAMETER
Power Supply Voltage
Output Source Current
Output Sink Current
LINEAR INTEGRATED CIRCUIT
RATINGS
UNIT
16
V
-50
mA
50
mA
SOP-8
570
Power Dissipation (Note2)
P
D
mW
TSSOP-8
580
Storage Temperature
T
STG
-55 ~ +125
C
Operating Temperature
T
OPR
-30 ~ +85
C
Notes: 1. Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.
2. When mounted on a 10cm square double-sided epoxy board.
RECOMMENDED OPERATING CONDITIONS
(T
A
=25C)
SYMBOL
V
CC
V
I
V
BR
I
O +
I
O-
C
PE
C
P
R
B
R
T
C
T
f
OSC
T
OPR
MIN
1.8
-0.2
-0.2
-40
TYP
MAX
15
1.0
V
CC
40
0.1
0.1
390
3.0
270
500
+25
UNIT
V
V
V
mA
mA
μF
μF
Ω
kΩ
pF
kHz
C
PARAMETER
Power Supply Voltage
Error Amplifier Input Voltage
BR/CTL Pin Input Voltage
Output Source Current
Output Sink Current
SCP Pin Capacitance
Phase Compensation Capacitance
Output Current Setting Resistance
Timing Resistance
Timing Capacitance
Oscillation Frequency
Operating Temperature
150
1.0
100
10
-30
5000
10.0
10000
1000
+85
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QW-R103-030.C
L2800
LINEAR INTEGRATED CIRCUIT
ELECTRICAL CHARACTERISTICS
(T
A
=25C, V
CC
=+2V)
MIN
TYP MAX UNIT
0.9
1.5
-0.7
0.9
-0.7
0.9
600
10
V
V
μA
V
μA
V
kHz
%
%
mV
mV
%
μA
V/V
MHz
V
V
μA
μA
%
V
V
V
V
mA
mA
kΩ
V
μA
μA
mA
μA
mA
PARAMETER
SYMBOL
TEST CONDITIONS
CIRCUIT TO PREVENT MALFUNCITION AT LOW INPUT OLTAGE (U.V.L.O)
Reset Voltage
V
R
Threshold Voltage
V
TH
Soft Start
Charging Current
I
CS
V
SCP
=0V
Voltage at soft start completion
V
TS
Short Circuit Detection(S.C.P.)
Charging Current
I
CPC
V
SCP
=0V
Threshold Voltage
V
TPC
SAWTOOTH WAVE OSCILLATOR(OSC)
Oscillation Frequency
f
OSC
R
T
=3.0kΩ, C
T
=270pF
Frequency Input Stability
f
DV
V
CC
=2V ~ 15V
Frequency Variation With Temperature
f
DT
T
A
=-30C ~ +85C
ERROR AMPLIFIER
Input Threshold Voltage
V
T
V
FB
=450mV
V
T
Input Stability
V
TDV
V
CC
=2V ~ 15V
V
T
Variation With Temperature
V
TDT
T
A
= -30C ~ +85C
Input Bias Current
I
B
V
IN
=0V
Voltage Gain
Av
Frequency Bandwidth
BW
A
V
=0dB
+
V
OM
Maximum Output Voltage Range
V
OM-
Output Source Current
I
OM+
V
FB
=0.45V
Output Sink Current
I
OM-
IDLE PERIOD ADJUSTMENT SECTION
Maximum Duty Cycle
t
DUTY
R
T
=3.0kΩ, C
T
=270pF, V
FB
=0.8V
OUTPUT SECTION
V
OH1
R
B
=390Ω, I
O
=-15mA
V
OH2
R
B
=750Ω, V
CC
=1.8V, Io= -10mA
Output Voltage
V
OL1
R
B
=390Ω, I
O
=15mA
V
OL2
R
B
=750Ω, V
CC
=1.8V, Io=10mA
+
Output Source Current
I
O
R
B
=390Ω, V
O
=0.9V
-
Output Sink Current
I
O
R
B
=390Ω, V
O
=0.3V
Pull Down Resistance
R
O
OUTPUT CURRENT SETTING SECTION/CONTROL SECTION
Pin Voltage
V
BR
R
B
=390Ω
Input Off Condition
I
OFF
Input On Condition
I
ON
Pin Current Range
I
BR
ENTIRE DEVICE
Stand-by Current
I
CCS
BR/CTL pin open or V
CC
Average Supply Current
I
CC
R
B
=390Ω
1.1
-1.5
0.7
-1.5
0.7
400
1.3
-1.0
0.8
-1.0
0.8
500
2
5
500
5
1
-0.2
100
6
0.87
0.05
-40
40
75
1.2
1.0
0.1
0.1
-30
60
30
0.3
480
520
20
1.0
145
-1.0
70
0.78
0.2
-24
24
65
1.0
0.8
85
0.2
0.2
-20
40
0.4
0
-45
-0.1
1
9.3
30
20
0.2
-20
-1.8
5.5
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QW-R103-030.C
L2800
DIAGRAM
LINEAR INTEGRATED CIRCUIT
HOW TO SET THE TIME CONSTANT FOR SHORT CIRCUIT DETECTION AND SOFT
START
1. SHORT CIRCUIT PROTECTION
Te error amplifier output (FB pin) is fixed at VOM
+
and capacitor C
PE
starts charging i the switching regulator
output suddenly drops due to load effect. The output pin is set low and the SCP pin stays low when the voltage at
the SCP pin reaches approximately 0.8V.
As the protection circuit operates, by resetting the power supply the circuit will be restored.
•Short circuit detection time
t
PE
[S]
≒
0.8×C
PE
[μF]
2. SOFT START
Once power on, the capacitor C
PE
which is connected to the SCP pin starts charging.The soft start setting
voltage is compared by the PWM comparator as the voltage’s proportion at the SCP pin with the sawtooth
waveform. The comparison controls the OUT pin’s ON duty,which is causing the soft start operation. During the
time for completion of soft start operation, the SCP pin’s voltage stays low, but the soft start setting voltage stays
high, and the circuit then enters the output short circuit detection wait state.
Soft start time (until the output ON duty reaches approximately 50%)
ts[S]
≒
0.35×C
PE
[μF]
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QW-R103-030.C
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