Datasheet

UNISONIC TECHNOLOGIES CO., LTD
L2800
LINEAR INTEGRATED CIRCUIT
SWITCHING REGULATOR
CONTROLLER(LOW VOLTAGE)

SOP-8
DESCRIPTION
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
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Copyright © 2013 Unisonic Technologies Co., Ltd
Package
Packing
SOP-8
SOP-8
TSSOP-8
TSSOP-8
Tube
Tape Reel
Tube
Tape Reel
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L2800
LINEAR INTEGRATED CIRCUIT

PIN CONFIGURATION

PIN DESCRIPTION
PIN NO.
1
2
3
4
5
6
7
8

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
BLOCK DIAGRAM
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L2800

LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATINGS (TA=25C)
PARAMETER
Power Supply Voltage
Output Source Current
Output Sink Current
RATINGS
UNIT
16
V
-50
mA
50
mA
SOP-8
570
Power Dissipation (Note2)
PD
mW
TSSOP-8
580
Storage Temperature
TSTG
-55 ~ +125
C
Operating Temperature
TOPR
-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.

SYMBOL
VCC
IO+
IO-
RECOMMENDED OPERATING CONDITIONS (TA=25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
SYMBOL
VCC
VI
VBR
IO +
IOCPE
CP
RB
RT
CT
fOSC
TOPR
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MIN
1.8
-0.2
-0.2
-40
TYP
MAX
15
1.0
VCC
40
150
1.0
100
10
-30
0.1
0.1
390
3.0
270
500
+25
5000
10.0
10000
1000
+85
UNIT
V
V
V
mA
mA
μF
μF
Ω
kΩ
pF
kHz
C
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LINEAR INTEGRATED CIRCUIT
ELECTRICAL CHARACTERISTICS (TA=25C, VCC=+2V)
PARAMETER
SYMBOL
TEST CONDITIONS
CIRCUIT TO PREVENT MALFUNCITION AT LOW INPUT OLTAGE (U.V.L.O)
Reset Voltage
VR
Threshold Voltage
VTH
Soft Start
Charging Current
ICS
VSCP=0V
Voltage at soft start completion
VTS
Short Circuit Detection(S.C.P.)
Charging Current
ICPC
VSCP=0V
Threshold Voltage
VTPC
SAWTOOTH WAVE OSCILLATOR(OSC)
Oscillation Frequency
fOSC
RT=3.0kΩ, CT=270pF
Frequency Input Stability
fDV
VCC=2V ~ 15V
Frequency Variation With Temperature
fDT
TA=-30C ~ +85C
ERROR AMPLIFIER
Input Threshold Voltage
VT
VFB=450mV
VT Input Stability
VTDV
VCC=2V ~ 15V
VT Variation With Temperature
VTDT
TA= -30C ~ +85C
Input Bias Current
IB
VIN=0V
Voltage Gain
Av
Frequency Bandwidth
BW
AV=0dB
VOM+
Maximum Output Voltage Range
VOMOutput Source Current
IOM+
VFB=0.45V
Output Sink Current
IOMIDLE PERIOD ADJUSTMENT SECTION
Maximum Duty Cycle
tDUTY
RT=3.0kΩ, CT=270pF, VFB=0.8V
OUTPUT SECTION
VOH1
RB=390Ω, IO=-15mA
VOH2
RB=750Ω, VCC=1.8V, Io= -10mA
Output Voltage
VOL1
RB=390Ω, IO=15mA
VOL2
RB=750Ω, VCC=1.8V, Io=10mA
Output Source Current
IO +
RB=390Ω, VO=0.9V
Output Sink Current
IORB=390Ω, VO=0.3V
Pull Down Resistance
RO
OUTPUT CURRENT SETTING SECTION/CONTROL SECTION
Pin Voltage
VBR
RB=390Ω
Input Off Condition
IOFF
Input On Condition
ION
Pin Current Range
IBR
ENTIRE DEVICE
Stand-by Current
ICCS
BR/CTL pin open or VCC
Average Supply Current
ICC
RB=390Ω
UNISONIC TECHNOLOGIES CO., LTD
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MIN
TYP MAX UNIT
1.1
1.3
0.9
1.5
V
V
-1.5
0.7
-1.0
0.8
-0.7
0.9
μA
V
-1.5
0.7
-1.0
0.8
-0.7
0.9
μA
V
400
500
2
5
600
10
kHz
%
%
480
520
20
24
500
5
1
-0.2
100
6
0.87
0.05
-40
40
mV
mV
%
μA
V/V
MHz
V
V
μA
μA
65
75
1.0
0.8
1.2
1.0
0.1
0.1
-30
60
30
-1.0
70
0.78
30
20
0.2
-20
0.3
-1.8
5.5
1.0
145
0.2
-24
85
%
0.2
0.2
-20
40
V
V
V
V
mA
mA
kΩ
0.4
0
-45
-0.1
V
μA
μA
mA
1
9.3
μA
mA
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LINEAR INTEGRATED CIRCUIT
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DIAGRAM

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 CPE 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
tPE[S]≒0.8×CPE[μF]
2. SOFT START
Once power on, the capacitor CPE 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×CPE[μF]
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
LINEAR INTEGRATED CIRCUIT
APPLICATION EXAMPLE
22μH
VO
5V
18kΩ
VIN
3V
-IN
0.1μF
SCP
33μF
Vcc
2kΩ
BR/CTL
390Ω
1
2
3
4
8
FB
7 OSC
6
GND
5
OUT
10μF
0.1μF
270pF
3kΩ
CTL
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L2800

LINEAR INTEGRATED CIRCUIT
TYPICAL CHARACTERISTICS
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
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