LT1306
Synchronous, Fixed Frequency
Step-Up DC/DC Converter
FEATURES
s
s
DESCRIPTIO
s
s
s
s
s
s
s
s
Output Disconnected from Input During Shutdown
Output Voltage Remains Regulated
When V
IN
> V
OUT
Controlled Input Current During Start-Up
300kHz Current Mode PWM Operation
Can Be Externally Synchronized
Internal 2A Switches
Operates with V
IN
as Low as 1.8V
Automatic Burst Mode Operation at Light Loads
Quiescent Current: 160µA
Shutdown Current: 9µA Typ
The LT
®
1306 is a fully integrated, fixed frequency syn-
chronous boost converter capable of generating 5V at 1A
from a Li-Ion cell. The device contains both the main
power switch and synchronous rectifier on chip and
automatically disconnects the output from the input in
shutdown, eliminating the need for external load discon-
nect circuitry. Additionally, the output remains regulated
when V
IN
exceeds V
OUT
, allowing difficult step-up/step-
down converter functions to be easily realized using a
single inductor.
The internal 300kHz oscillator of the LT1306 can be easily
synchronized to an external clock from 425kHz to 500kHz.
This allows switching harmonics to be tightly controlled
and eliminates any beat frequencies that may result from
a multifrequency system. The LT1306 automatically shifts
into power saving Burst Mode
TM
operation at light loads.
At heavy loads the LT1306 operates in fixed frequency
current mode. No-load quiescent current is 160µA and
reduces to 9µA in shutdown mode.
The LT1306 is available in an SO-8 package.
APPLICATIO S
s
s
s
s
Satellite Phones
Portable Instruments
Personal Digital Assistants
Palmtop Computers
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
TYPICAL APPLICATION
D1
L1
10µH
C1
1µF
90
85
EFFICIENCY (%)
1-CELL
Li-Ion
V
IN
S/S
SW
LT1306
CAP
OUT
R1
768k
FB
GND
R2
249k
5V
1A
+
C
IN1
22µF
C
IN2
0.1µF
V
C
R3
118k
C
Z
68nF
+
C
O1
220µF
C
O2
1µF
C
IN1
: AVX TAJC226M010
C
O1
: AVX TPSE227M010R0100
C
IN1
, C
O2
: CERAMIC
C1: AVX TAJA105K020
D1: MMBD914LT1
L1: CTX10-2
C
P
68pF
1306 F01
Figure 1. Single Li-Ion Cell to 5V Converter
U
Efficiency
V
IN
= 4.2V
V
IN
= 3.6V
V
IN
= 2.6V
80
75
70
65
60
1
10
100
LOAD CURRENT (mA)
1000
1306 TA01
U
U
+
V
O
= 5V
L1 = 10µH
(FIGURE 1)
1
LT1306
ABSOLUTE
MAXIMUM
RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW
V
C
1
FB 2
V
OUT
3
GND 4
8 S/S
7 V
IN
6 CAP
5 SW
V
IN
Voltage ............................................................. 10V
S/S Voltage ............................................................... 7V
FB Voltage .............................................................. 10V
V
OUT
Voltage .......................................................... 5.5V
Junction Temperature .......................................... 125°C
Operating Temperature Range (Note 2) .. – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LT1306ES8
S8 PART MARKING
1306
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 90°C/ W
Consult factory for Industrial and Military grade parts.
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 2.5V, V
S/S
= V
IN
, V
C
open unless otherwise noted.
PARAMETER
Reference Voltage
Reference Line Regulation
FB Input Bias Current
Error Amplifier Transconductance
Error Amplifier Output Source Current
Error Amplifier Output Sink Current
Error Amplifier Output Clamp Voltage
V
IN
Undervoltage Lockout Threshold
Idle Mode Output Leakage Current
Output Source Current in Shutdown
Switching Frequency
Maximum Duty Cycle
Switch Current Limit
Burst Mode Operation Switch Current Limit
Switch V
CESAT
Rectifier V
CESAT
Stepdown Mode Rectifier Voltage
Switch and Rectifier Leakage Current
I
SW
= 2A
I
SW
= 2A
V
OUT
= 0V, I
SW
= 1A
V
OUT
= 2.2V, I
SW
= 1A
V
OUT
= 0V, V
IN
= V
SW
= 7V, V
CAP
= 7.2V, V
S/S
= 0V
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
Measured at the FB Pin
1.8V
≤
V
IN
≤
7V
V
FB
= V
REF
∆I
=
±0.2µA
V
FB
= 1V, V
C
= 0.8V
V
FB
= 1.5V, V
C
= 0.8V
V
FB
= 1V
V
FB
= 1.5V, V
OUT
= 5.5V, V
SW
= 1.7V
V
OUT
= 0V, V
IN
= V
SW
= 7V, V
CAP
= 7.2V, V
S/S
= 0V
1.8V
≤
V
IN
≤
7V, 0°C
≤
T
A
≤
85°C
1.8V
≤
V
IN
≤
7V, T
A
= – 40°C
V
FB
= 1V, 0°C
≤
T
A
≤
85°C
V
FB
= 1V, T
A
= – 40°C
Duty Cycle = 0.1 (Note 3)
Duty Cycle = 0.8 (Note 3)
q
q
q
q
q
MIN
1.22
TYP
1.24
0.002
10
MAX
1.26
0.1
25
220
11
11
1.38
1.8
15
–3
415
390
UNITS
V
%/V
nA
µΩ
–1
µA
µA
V
V
µA
µA
kHz
kHz
%
%
A
A
80
5
5
1.18
1.55
150
7.5
7.5
1.28
6
260
225
80
65
2.3
2.0
310
305
90
80
250
0.45
0.49
0.3 + V
IN
1.3
0.1
0.575
0.675
0.7 + V
IN
1.8
20
2
U
W
U
U
W W
W
mA
V
V
V
V
µA
LT1306
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 2.5V, V
S/S
= V
IN
, V
C
open unless otherwise noted.
PARAMETER
S/S Pin Current
Shutdown Pin Input High Voltage
Shutdown Pin Input Low Voltage
Shutdown Delay
Synchronization Frequency Range
Operating Supply Current
Quiescent Supply Current
Shutdown Supply Current
CAP Pin Leakage Current
Output Boost-to-Stepdown Threshold
Output Stepdown-to-Boost Threshold
Note 1:
Absolute Maximum Ratings are those values beyond which the life
to the device may be impaired.
Note 2:
The LT1306E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the – 40°C to 85°C operating
V
S/S
= V
IN
, V
FB
= 1.5V
V
S/S
= 0V
V
IN
= V
CAP
= 7V, V
S/S
= 2.5V, I
SW
= 0
q
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
V
S/S
= V
IN
V
S/S
= 0V
MIN
TYP
MAX
6
–3
UNITS
µA
µA
V
V
µs
kHz
mA
µA
µA
µA
V
V
1.2
0.45
12
425
4.5
160
9
V
IN
V
IN
– 0.1
20
50
500
8
250
16
10
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3:
Switch current limit guaranteed by design/correlation to static
tests.
TYPICAL PERFORMANCE CHARACTERISTICS
Maximum Load Current vs
Input Voltage
1.5
V
O
= 5V
REFERENCE VOLTAGE (V)
V
O
= 3.3V
I
LOADMAX
(A)
1.0
I
S/S
(µA)
0.5
L = 10µH
T
J
= 125°C
0
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0
V
IN
(V)
1306 • G01
U W
T
A
= 25°C
T
A
= 50°C
Reference Voltage vs
Temperature
1.239
1.238
1.237
1.236
1.235
1.234
1.233
1.232
1.231
–40
–20
0
20
40
60
80
100
5
4
3
2
1
0
–1
–2
–3
–4
–5
S/S Pin Current vs S/S Pin Voltage
TA = –40°C
TA = 25°C
TA = 85°C
0
1
TEMPERATURE (°C)
1306 • G02
2
3
V
S/S
(V)
4
5
1306 • G03
3
LT1306
TYPICAL PERFORMANCE CHARACTERISTICS
Shutdown Supply Current vs
Input Voltage
40
35
SUPPLY CURRENT (µA)
5.0
TA = 25°C
S/S CURRENT (µA)
V
S/S
= 2.5V
2.5
IDLE-MODE SUPPLY CURRENT (µA)
30
25
20
15
TA = –40°C
10
5
0
2
4
6
8
INPUT VOLTAGE (V)
10
12
1306 • G04
TA = 85°C
Oscillator Frequency Line
Regulation
320
315
310
305
315
FREQUENCY (kHz)
FREQUENCY (kHz)
295
290
285
280
275
DUTY RATIO (%)
310
305
300
0
1
2
3
4
5
V
IN
(V)
1306 • G07
6
7
Maximum Allowable Rise Time of
Synchronizing Pulse
600
500
3.0
MAXIMUM RISE TIME (ns)
SWITCH VOLTAGE (V)
400
300
200
100
0
CURRENT LIMIT (A)
1
3.5
1.5
2.0
2.5
3.0
SYNCHRONIZING PULSE AMPLITUDE (V)
1306 • G10
4
U W
8
9
10
S/S Pin Current vs Temperature
155
Idle-Mode Supply Current vs
Temperature
150
145
0
V
S/S
= 0V
–2.5
– 40
140
–20
0
20
40
60
TEMPERATURE (°C)
80
100
135
–40
–20
0
20
40
60
80
100
TEMPERATURE (°C)
1306 • G05
1306 • G06
Frequency vs Temperature
95
90
85
80
75
70
65
270
265
–40
–20
40
0
60
20
TEMPERATURE (°C)
80
100
Maximum Duty Ratio
V
IN
= 2.5V
300
60
–40 –20
40
20
60
0
TEMPERATURE (°C)
80
100
1306 • G08
1306 • G09
Current Limit vs Duty Cycle
0.7
T
A
= 25°C
0.6
2.8
0.5
0.4
Switch Saturation Voltage
vs Current
TA = 25°C
2.6
TA = 85°C
0.3
0.2
0.1
0
TA = –40°C
2.4
2.2
2.0
0
10
20
30 40 50 60
DUTY CYCLE (%)
70
80
90
0
0.5
2.0
1.5
SWITCH CURRENT (A)
1.0
2.5
1306 • G12
1306 • G11
LT1306
TYPICAL PERFORMANCE CHARACTERISTICS
Rectifier Saturation Voltage
vs Current
0.7
0.6
RECTIFIER VOLTAGE (V)
1.90
TA = 85°C
RECTIFIER VOLTAGE (V)
0.5
0.4
TA = –40°C
0.3
0.2
0.1
0
0
0.5
2.0
1.5
RECTIFIER CURRENT (A)
1.0
2.5
1306 • G13
TA = 25°C
Start-Up to Shutdown Transient
Response*
V
S/S
5V/DIV
V
SW
5V/DIV
I
L
2A/DIV
V
SW
5V/DIV
V
O
5V/DIV
V
IN
= 2.5V
1ms/DIV
*Notice that the Input Start-Up Current is well Controlled and the
Output Voltage Falls to Zero in Shutdown.
U W
Stepdown-Mode Rectifier Voltage
vs Current
1.85
1.80
1.75
1.70
1.65
1.60
1.55
0
0.5
1.5
RECTIFIER CURRENT (A)
1.0
2.0
1306 • G14
Continuous-Conduction Mode
Switching Waveforms in Boost
Operation
V
IN
= 6V
V
OUT
= 5V
T
A
= 25°C
V
SW
5V/DIV
I
L
0.5A/DIV
V
O
0.1V/DIV
AC
V
IN
= 4.2V
V
O
= 5V
2µs/DIV
Continuous-Conduction Mode
Switching Waveforms in
Stepdown Mode
LOAD
CURRENT
0.5A/DIV
DC
INDUCTOR
CURRENT
1A/DIV
Transient Response of the
Converter in Figure 1 with a
50mA to 800mA Load Step
I
L
0.5V/DIV
V
O
50mV/DIV
AC
OUTPUT
0.1V/DIV
AC
V
IN
= 6V
V
O
= 5V
2µs/DIV
V
IN
= 3.6V
V
O
= 5V
1ms/DIV
5
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