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LT1111
Datasheet
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Linear Technology LT1111 Datasheet

LT1111
0
LOAD CURRENT (mA)
0
1
OUTPUT VOLTAGE (V)
2
3
4
5
6
50 100 150 200
LT1111 • TA02
25 75 125 175
VIN = 2V 2.2 2.4 2.6 2.8 3V
Micropower
DC/DC Converter
Adjustable and Fixed 5V, 12V
EATU
F
■
Operates at Supply Voltages from 2V to 30V
■
72kHz Oscillator
■
Works with Surface Mount Inductors
■
Only Three External Components Required
■
Step-Up or Step-Down Mode
■
Low-Battery Detector Comparator On-Chip
■
User Adjustable Current Limit
■
Internal 1A Power Switch
■
Fixed or Adjustable Output Voltage Versions
■
Space Saving 8-Pin MiniDIP or SO-8 Package
PPLICATI
A
■
3V to 5V, 5V to 12V Converters
■
9V to 5V, 12V to 5V Converters
■
Remote Controls
■
Peripherals and Add-On Cards
■
Battery Backup Supplies
■
Uninterruptible Supplies
■
Laptop and Palmtop Computers
■
Cellular Telephones
■
Portable Instruments
■
Flash Memory VPP Generators
RE
S
O
U S
DUESCRIPTIO
The LT1111 is a versatile micropower DC/DC converter. The device requires only three external components to deliver a fixed output of 5V or 12V. Supply voltage ranges from 2V to 12V in step-up mode and to 30V in step-down mode. The LT1111 functions equally well in step-up, step­down, or inverting applications.
The LT1111 oscillator is set at 72kHz, optimizing the device to work with off-the-shelf surface mount inductors. The device can deliver 5V at 100mA from a 3V input in step-up mode or 5V at 200mA from a 12V input in step­down mode.
Switch current limit can be programmed with a single resistor. An auxiliary open-collector gain block can be configured as a low-battery detector, linear post regulator, undervoltage lock-out circuit, or error amplifier.
For input sources of less than 2V use the LT1110.
3V INPUT
U
O
A
PPLICATITYPICAL
All Surface Mount 3V to 5V Step-Up Converter
SUMIDA
+
10 F*
*OPTIONAL
µ
I
GND SW2
V
LIM
LT1111CS8-5
IN
SENSE
CD54-220M
SW1
22µH
+
5V 100mA
33 F
µ
LT1111 • TA01
Typical Load Regulation
1
L T 1111
A
W
O
LUTEXI T
S
A
WUW
ARB
U G
I
S
Supply Voltage (VIN)............................................... 36V
SW1 Pin Voltage (V SW2 Pin Voltage (V
) ......................................... 50V
SW1
) ............................ – 0.5V to V
SW2
Feedback Pin Voltage (LT1111) ............................. 5.5V
Switch Current....................................................... 1.5A
Maximum Power Dissipation ............................ 500mW
WU
/
PACKAGE
I
1
LIM
V
2
IN
SW1
3
SW2
4
J8 PACKAGE
8-LEAD CERAMIC DIP
T
JMAX
T
JMAX
O
RDER I FOR ATIO
TOP VIEW
FB (SENSE)*
8
SET
7
A0
6
GND
5
N8 PACKAGE
8-LEAD PLASTIC DIP
*FIXED VERSIONS
= 150°C, θJA = 120°C/W (J)
= 90°C, θJA = 130°C/W (N)
ORDER PART
NUMBER
LT1111CN8 LT1111CN8-5 LT1111CN8-12 LT1111MJ8 LT1111MJ8-5 LT1111MJ8-12
Operating Temperature Range
LT1111C............................................... 0°C to 70°C
IN
LT1111I ......................................... –40°C to 105°C
LT1111M ....................................... –55°C to 125°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
U
I
1
LIM
V
2
IN
SW1
3
SW2
4
8-LEAD PLASTIC SO
*FIXED VERSION
T
JMAX
TOP VIEW
8
7
6
5
S8 PACKAGE
= 90°C, θJA = 150°C/W
FB (SENSE)* SET A0 GND
ORDER PART
NUMBER
LT1111CS8 LT1111CS8-5 LT1111CS8-12
S8 PART MARKING
1111 11115 11111
Consult factory for Industrial grade parts
LECTRICAL C CHARA TERIST
E
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
Q
V
IN
V
OUT
f
OSC
DC Duty Cycle: Step-Up Mode Full Load 43 50 59 %
t
ON
V
SAT
I
FB
I
SET
V
OL
Quiescent Current Switch OFF 300 400 µA Input Voltage Step-Up Mode ● 2.0 12.6 V
Comparator Trip Point Voltage LT1111 (Note 1) ● 1.20 1.25 1.30 V Output Sense Voltage LT1111-5 (Note 2) ● 4.75 5.00 5.25 V
Comparator Hysteresis LT1111 ● 8 12.5 mV Output Hysteresis LT1111-5 ● 32 50 mV
Oscillator Frequency 54 72 88 kHz
Step-Down Mode 24 34 50 %
Switch ON Time: Step-Up Mode I
Step-Down Mode V
SW Saturation Voltage, Step-Up Mode VIN = 3.0V, ISW = 650mA 0.5 0.65 V
SW Saturation Voltage, Step-Down Mode VIN = 12V, ISW = 650mA 1.1 1.5 V Feedback Pin Bias Current LT1111, VFB = 0V ● 70 120 nA
Set Pin Bias Current V Gain Block Output Low I
ICS
VIN = 3V, Military or Commercial Version
Step-Down Mode
LT1111-12 (Note 2) ● 11.40 12.00 12.60 V
LT1111-12 ● 75 120 mV
Tied to V
LIM
OUT
VIN = 5.0V, ISW = 1A 0.8 1.0 V
SET
SINK
IN
, = 5V, VIN = 12V 3.3 5 7.8 µs
= V
REF
= 300µA, V
= 1.00V ● 0.15 0.4 V
SET
● 30.0 V
579 µs
● 70 300 nA
2
LT1111
LECTRICAL C CHARA TERIST
E
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Reference Line Regulation 5V ≤ VIN ≤ 30V ● 0.02 0.075 %/V
A
V
I
LIM
VIN = 3V, –55°C ≤ TA ≤ 125°C unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
Q
f
OSC
DC Duty Cycle: Step-Up Mode Full Load ● 40 50 62 %
t
ON
V
SAT
Gain Block Gain RL = 100k (Note 3) ● 1000 6000 V/V Current Limit 220Ω from I Current Limit Temperature Coefficient ● –0.3 %/°C Switch OFF Leakage Current Measured at SW1 Pin, V Maximum Excursion Below GND I
Quiescent Current Switch OFF ● 300 500 µA Oscillator Frequency ● 45 72 100 kHz
Step-Down Mode Switch ON Time: Step-Up Mode I
Step-Down Mode V Reference Line Regulation 2V ≤ VIN ≤ 5V, 25°C ≤ TA ≤ 125°C 0.2 0.4 %/V
SW Saturation Voltage, Step-Up Mode 0°C ≤ TA ≤ 125°C, ISW = 500mA, 0.5 0.65 V
SW Saturation Voltage, Step-Down Mode VIN = 12V, 0°C ≤ TA ≤ 125°C 1.5 V
ICS
VIN = 3V, Military or Commercial Version
2V ≤ VIN ≤ 5V 0.20 0.400 %/V
to V
LIM
IN
= 12V 1 10 µA
SW1
≤ 10µA, Switch OFF –400 –350 mV
SW1
● 20 55 %
Tied to V
LIM
OUT
2.4V ≤ VIN ≤ 5V, TA = –55°C 0.8 %/V
= –55°C, ISW = 400mA
T
A
ISW = 500mA TA = –55°C 2.0 V
IN
= 5V, VIN = 12V ● 39µs
● 5711 µs
400 mA
LT1111M
VIN = 3V, 0°C ≤ TA ≤ 70°C unless otherwise noted.
LT1111C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
Q
f
OSC
DC Duty Cycle: Step-Up Mode Full Load ● 43 50 59 %
t
ON
V
SAT
The ● denotes specifications which apply over the full operating temperature range.
Note 1: This specification guarantees that both the high and low trip points of the comparator fall within the 1.20V to 1.30V range.
Quiescent Current Switch OFF ● 300 450 µA Oscillator Frequency ● 54 72 95 kH
Step-Down Mode
Switch ON Time: Step-Up Mode I
Step-Down Mode V
Reference Line Regulation 2V ≤ VIN ≤ 5V ● 0.2 0.7 %/V SW Saturation Voltage, Step-Up Mode VIN = 3V, ISW = 650mA ● 0.5 0.65 V
SW Saturation Voltage, Step-Down Mode VIN = 12V, ISW = 650mA ● 1.1 1.50 V
Tied to V
LIM
OUT
IN
= 5V, VIN = 12V ● 3.3 5 7.8 µs
Note 2: The output voltage waveform will exhibit a sawtooth shape due to the comparator hysteresis. The output voltage on the fixed output versions will always be within the specified range.
Note 3: 100k resistor connected between a 5V source and the A0 pin.
● 24 34 50 %
● 5.0 7 9.0 µs
3
L T 1111
TEMPERATURE (°C)
ON TIME (µs)
–50 –25 0 25
LT111 • TPC03
50 75 100
125
10
9.5
9.0
8.5
8.0
7.5
7.0
6.5
6.0
5.5
5.0
SWITCH CURRENT (A)
SATURATION VOLTAGE (V)
0 0.2
0.4 0.6
LT1111 • TPC06
0.8
1.0
1.2
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
1.4
VIN = 3V
V
IN
= 2V
V
IN
= 5V
SWITCH ON TIME (µs)
OSCILLATOR FREQUENCY (KHz)
4
567
LT1111 • TPC09
89
100
90
80
70
60
50
40
10 11 12
–55°C ≤ TA ≤ 125°C
0°C ≤ TA ≤ 70°C
UW
Y
PICA
100
90
80
70
60
OSCILLATOR FREQUENCY (KHz)
50
40
60 58 56 54 52 50 48
DUTY CYCLE (%)
46 44 42
40
–50 –25 0 25
LPER
F
O
R
AT
CCHARA TERIST
E
C
ICS
Oscillator Frequency Oscillator Frequency Switch ON Time
75
74
73
72
71
70
FREQUENCY (KHz)
69
68
–50
–25 0
TEMPERATURE (°C)
25
50
75
100
LT1111 • TPC01
125
67
0
36
15 18 21
912 INPUT VOLTAGE (V)
242730
LT1111 • TPC02
Saturation Voltage Saturation Voltage
Duty Cycle Step-Up Mode Step-Up Mode
1.0 VIN = 3V
0.9 I
650mA
=
SW
0.8
0.7
0.6
0.5
0.4
0.3
SATURATION VOLTAGE (V)
0.2
0.1
50 75 100
TEMPERATURE (°C)
125
LT1111 • TPC04
0
–50 – 25 0 25
TEMPERATURE (°C)
50 75 100
LT1111 • TPC05
125
Switch ON Voltage Switch ON Voltage Minimum/Maximum Frequency Step-Down Mode Step-Down Mode vs ON Time
2.00 VIN = 12V I
SW
1.75
1.50
1.25
ON VOLTAGE (V)
1.00
0.75
0.50
–50 –25 0 25
4
650mA
=
TEMPERATURE (°C)
50 75 100
LT1111 • TPC07
125
1.4 VIN = 12V
1.2
1.0
0.8
0.6
ON VOLTAGE (V)
0.4
0.2
0
0 0.2 0.4 0.6
SWITCH CURRENT (A)
0.8 1.0
LT1111 • TPC08
UW
Y
PICA
400
380 360 340 320
300 280 260
QUIESCENT CURRENT (µA)
240 220 200
LPER
F
O
R
AT
CCHARA TERIST
E
C
ICS
Quiescent Current Quiescent Current vs R
500
450
400
350
300
250
200
QUIESCENT CURRENT (µA)
150
6
3
0
912151821242730 INPUT VOLTAGE (V)
LT1111 • TPC10
100
–50
–25
0 25 50 75 100 125
TEMPERATURE (°C)
LT1111 • TPC11
Set Pin Bias Current Feedback Bias Current
100
90 80 70 60 50 40 30
BIAS CURRENT (nA)
20 10
0
–25
–50
0 25 50 75 100 125
TEMPERATURE (°C)
LT1111 • TPC13
100
90 80 70 60 50 40 30
BIAS CURRENT (nA)
20 10
0
–25
–50
Maximum Switch Current
LIM
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6 STEP-DOWN
0.5
SWITCH CURRENT (A)
0.4
0.3
0.2
0.1
10
0 25 50 75 100 125
TEMPERATURE (°C)
V
IN
= 12V
STEP-UP 2V ≤ V
100
R
LIM
LT1111 • TPC14
(Ω)
IN
≤ 5V
LT1111
1000
LT1111 • TPC12
U
PI
I
FUUC
(Pin 1): Connect this pin to VIN for normal use. Where
LIM
TI
O
U
S
lower current limit is desired, connect a resistor between I
and VIN. A 220Ω resistor will limit the switch current
LIM
to approximately 400mA.
V
(Pin 2): Input Supply Voltage.
IN
SW1 (Pin 3): Collector of Power Transistor. For step-up
mode connect to inductor/diode. For step-down mode connect to VIN.
SW2 (Pin 4): Emitter of Power Transistor. For step-up
mode connect to ground. For step-down mode connect to inductor/diode. This pin must never be allowed to go more than a Schottky diode drop below ground.
GND (Pin 5): Ground. A0 (Pin 6): Auxiliary Gain Block (GB) Output. Open collector,
can sink 300µA. SET (Pin 7): GB Input. GB is an op amp with positive input
connected to SET pin and negative input connected to
1.25V reference. FB/SENSE (Pin 8): On the LT1111 (adjustable) this pin
goes to the comparator input. On the LT1111-5 and LT1111-12, this pin goes to the internal application resistor that sets output voltage.
5
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