UTC LT1304/LT1304-3.3V/LT1304-5.0V
LINEAR INTEGRATED CIRCUIT
MICROPOWER DC/DC
CONVERTERS WITH
LOW-BATTERY DETECTOR
ACTIVE IN SHUTDOWN
DESCRIPTION
The UTC LT1304 is a micropower step-up DC/DC
converter ideal for use in small, low voltage,
battery-operated systems. The devices operate from a
wide input supply range of 1.5V to 8V.
The UTC LT1304-3.3 and LT1304-5.0 generate
regulated outputs of 3.3V and 5V and the adjustable
LT1304 can deliver output voltages up to
25V.Quiescent current,120
μ
A
in active mode,
decreases to just 10
μ
A in shutdown with the
low-battery detector still active. Peak switch current,
internally set at 1A,can be reduced by adding a single
resistor from the I
LIM
pin to ground. The high speed
operation of the UTC LT1304 allows the use of small,
surface-mountable inductors and capacitors.
SOP-8
DIP-8
FEATURES
*5V at 200mA from two cells.
*10μA quiescent current in shutdown.
*Operates with V
IN
as low as1.5V
*Low battery detector active in shutdown
*Low switch V
CESAT
:370mV at 1A typical.
*120μA quiescent current in active mode.
*Switching frequency up to 300kHz
*Programmable peak current with one resistor.
.
APPLICATIONS
*2-,3-,or 4-cell to 5V or 3.3V step-up
*Portable instruments
*Bar code scanners
*Palmtop computers
*Diagnostic medical instrumentation.
*Personal data communicators/computers.
PIN CONFIGURATION
LBI
LBO
V
IN
SW
1
2
3
4
8
7
6
5
FB(SENSE)*
SHDN
I
L I M
GND
UTC
UNISONIC TECHNOLOGIES CO., LTD.
1
QW-R103-018,A
UTC LT1304/LT1304-3.3V/LT1304-5.0V
LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATINGS
PARAMETER
Input Voltage
SW Voltage
FB Voltage(LT1304)
I
LIM
Voltage(LT1304-3.3/LT1304-5.0)
SHDN Voltage
LBI Voltage
LBO Voltage
Maximum Power Dissipation
Junction Temperature
Operating Temperature Range
Storage Temperature Range
Lead Temperature (soldering,10sec)
SYMBOL
V
IN
RATING
8
-0.4 ~ +25
V
IN
+0.3
5
6
V
IN
8
500
125
0 ~ 70
-65 ~ +150
300
UNIT
V
V
V
V
V
V
V
mW
P
D
Tj
Topr
Tstg
°C
°C
°C
°C
ELECTRICAL CHARACTERISTICS
(V
IN
=2V,V
SHDN
=2V Unless otherwise noted.)
PARAMETER
Minimum Operating Voltage
Operating Voltage Range
Quiescent Current
Quiescent Current In Shutdown
Comparator Trip Point
FB Pin Bias Current
Sense Pin Leakage in Shutdown
Line Regulation
LBI Input Threshold
LBI Bias Current
LBI Input Hysteresis
LBO Output Voltage Low
LBO Output Leakage Current
SHDN Input Voltage High
SHDN Input Voltage Low
SHDN Pin Bias Current
Switching Off Time
Switch On Time
Maximum Duty Cycle
Peak Switch Current
Switch Saturation Voltage
*
*
*
*
*
V
SHDN
=2V,Not switching
V
SHDN
=0V,V
IN
=2V
V
SHDN
=0V,V
IN
=5V
1.22
V
SHDN
=0V,Fixed Output Versions
1.8V≤V
IN
≤8V
Falling Edge
1.10
120
7
27
1.24
10
0.002
0.04
1.17
6
35
I
SINK
=500µA
LBI=1.5V,LBO=5V
1.4
0.4
V
SHDN
=5V
V
SHDN
=0V
Current Limit Not Asserted
Current Limit Not Asserted
I
LIM
Pin Open,V
IN
=5V
20K from I
LIM
to GND
Isw=1A
*
Isw=700mA
-5
1
4
76
0.8
5
-2
1.5
6
80
1
500
0.37
0.26
0.35
2
8
88
1.2
8
0.2
0.01
TEST CONDITIONS
MIN
TYP
1.5
MAX
1.65
8
200
15
50
1.26
25
1
0.15
1.25
20
65
0.4
0.1
UNIT
V
V
µA
µA
µA
V
nA
µA
%/V
V
nA
mV
V
µA
V
V
µA
µA
µs
µs
%
A
mA
V
V
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
UTC
UNISONIC TECHNOLOGIES CO., LTD.
2
QW-R103-018,A
UTC LT1304/LT1304-3.3V/LT1304-5.0V
LINEAR INTEGRATED CIRCUIT
PARAMETER
Switch Leakage
TEST CONDITIONS
Switch off, Vsw=5V
MIN
TYP
0.01
MAX
7
UNIT
µA
The * denotes specifications which apply over the 0
°C
to 70°C operating temperature range.
PIN FUNCTIONS
PIN No.
1
2
3
4
5
6
7
SYMBOL
LBI
LBO
V
IN
SW
GND
I
LIM
DESCRIPTION
Low Battery Detector Input. When voltage on this pin is less than
1.17V,detector output is low
Low Battery Detector Output. Open collector can sink up to 500µA.Low
battery detector remains active when device is shut down.
Input Supply. Must be bypassed close (<0.2”) to the pin. See required layout
in the Typical Applications
Collector of Power NPN. Keep copper traces on this pin short and direct to
minimize RFI
Device Ground. Must be low impedance; solder directly to ground plane
Current Limit Set Pin. Float for 1A peak switch current; a resistor to ground
will lower peak current
SHDN
Shutdown Input. When low, switching regulator is turned off. The
low-battery detector remains active. The SHDN input should not be left
floating. If SHDN is not used, tie the pin to V
IN
On the LT1304 (adjustable) this pin goes to the comparator input. On the
fixed-output versions, the pin connects to the resistor divider which sets output
voltage. The divider is disconnected from the pin during shutdown.
8
FB/SENSE
TYPICAL APPLICATION
2-Cell to 5V Step-Up Converter with Low-Battery Detect
22μH
D1
1N5817
90
80
EFFICIENCY (%)
Efficiency
499K
3
1 VIN
LBI
+
2 CELLS
100μF
4
SW
8
SENSE
100K
+
5V
200mA
100μF
LBO
LOW WHEN
VBAT
＜2.2V
70
604K
LT1304-5.0
6
LIM
NC
I
IBO 2
SHDN
7
SHUTDOWN
GND
5
60
50
40
0.01
V IN =3.3V
V IN =2.5V
V IN =1.8V
1
10
100 500
LOAD CURRENT(mA)
UTC
UNISONIC TECHNOLOGIES CO., LTD.
3
QW-R103-018,A
UTC LT1304/LT1304-3.3V/LT1304-5.0V
LINEAR INTEGRATED CIRCUIT
TYPICAL PERFORMANCE CHARACTERISTICS
Switch Saturation Voltage
500
Ta =25
℃
Saturation Voltage (mV)
1.2
400
1.1
Peak Current (A)
300
1.0
0.9
0.8
0.7
0.6
-50
1.3
Peak Switch Current Limit
200
100
0
0
0.2
0.4
0.6
0.8
1.0
1.2
Switch Current (A)
O n-and O ff-times
8
7
6
5
4
3
2
1
0
-50
-25
0
25
50
75
100
O ff-T ime
Feedback Voltage (V)
Maximum O n-Time
-25
0
25
50
75
100
Temperature(
℃
)
Feedback Voltage
1.250
1.245
1.240
1.235
1.230
1.225
1.220
1.215
1.210
1.205
1.200
-50
-25
0
25
50
75
100
T ime (
μ
s)
Temperature(
℃
)
Feedback Pin Bias Current
20
18
16
14
Bias Current (nA)
Supply Current
µ
s)
12
10
8
6
4
2
0
-50
-25
0
25
50
75
100
200
150
250
300
Ta =25
℃
Temperature(
℃
)
Supply Current
VSHDN=VN
NOT SW ITCHING
100
VSHDN= 0 V
50
0
0
1
2
3
4
5
6
7
8
Temperature(
℃
)
Input Voltage (V)
UTC
UNISONIC TECHNOLOGIES CO., LTD.
4
QW-R103-018,A
UTC LT1304/LT1304-3.3V/LT1304-5.0V
LINEAR INTEGRATED CIRCUIT
Load Transient
Response
OUT
V
100mV / DIV
AC COUPLED
O UT
V
100mV/DIV
AC COUPLED
Burst Mode Operation
Vs w
5V/DIV
I
L
500mA/DIV
100
μ
s / DIV
0
I
LOAD
200mA
0
20μ s/DIV
VIN=2.5V
VOUT=5V
ILOAD=185mA
L=22
μ
H
BLOCK DIAGRAMS
VIN
+
C1
L1
D1
+
VOUT
C2
2
LBO
1.5V
UNDERVOLTA
GELOCKOUT
3
VIN
4
SW
1
LBI
+
-
1.17V
A2
A3
BIAS
-1V
36mV
+
R2
-
1K
OFF
Q3
1K
R1
7.2Ω
R3
8
R4
FB
-
A1
+
1.24V
VREF
ENABLE
TIMERS
6μs ON
1.5μs OFF
DRIVER
Q2
×1
Q1
×200
SHUTDOWN
7
SHDN
6
ILIM
5
GND
Figure 1. LT1304 Block Diagram. Independent Low-Battery Detector A3 Remains Alive When Device Is in Shutdown
UTC
UNISONIC TECHNOLOGIES CO., LTD.
5
QW-R103-018,A
嵌入式系统
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