LINEAR TECHNOLOGY LT1501 Technical data

查询LT1500供应商

FEATURES

LT1500/LT1501

Adaptive-Frequency

Current Mode Switching Regulators

U

DESCRIPTION

■

Low Noise Adaptive-Frequency Current Mode
Operation Avoids Low Frequency Noise at
Most Load Currents

■

Can Be Externally Synchronized (LT1500)

■

Micropower Quiescent Current: 200µA

■

Shutdown Current: 8µA Typ

■

Internal Loop Compensation

■

Low-Battery Comparator Active in Shutdown

■

Minimum Input Voltage: 1.8V Typ

■

Additional Negative Voltage Feedback Pin (LT1500)

■

Up to 500kHz Switching Frequency

■

Uses Low Profile, Low Cost Surface Mount Inductors

U

APPLICATIONS

■

Portable Instrumentation

■

Battery Operated Systems

■

PDA’s

■

Standby Power

The LT®1500 is an adaptive-frequency current mode step­up switching regulator with an internal power switch that
is rated up to 700mA. In contrast to pulse skipping
switching regulators, the LT1500 uses a current mode
topology that provides lower noise operation and im­proved efficiency. Only at very light loads is Burst Mode

TM

activated to give high efficiency and micropower opera­tion. High switching frequency (up to 500kHz) allows very
small inductors to be used, along with ceramic capacitors
if desired.

The LT1500 operates with input voltages from 1.8V to 15V
and has only 200µ A operating current dropping to 8µA in
shutdown. A low-battery comparator is included which
stays alive in shutdown. A second output feedback pin
with negative polarity allows negative output voltages to
be regulated when the switcher is connected up as a Cuk
or a flyback converter.

Two package types are available. The LT1500 comes in a
14-pin SO package, with two options available for fixed
output (3.3V or 5V) or adjustable operation. A reduced
feature part, the LT1501, comes in the smaller 8-pin SO
package with internal frequency compensation. It is also
available in adjustable and fixed output voltage versions.

, LTC and LT are registered trademarks of Linear Technology Corporation.

Burst Mode is a trademark of Linear Technology Corporation.

TYPICAL APPLICATION

2 EACH

NiCd OR

ALKALINE

CELLS

+

U

33µF*
6V

2-Cell to 5V Converter

V

301k
1%

301k
1%

(USE EXTERNAL PULL-UP)

IN

SHDN

LT1501-5

LBI

LBO

1nF

LOW-BATTERY FLAG

I

SENSE

GND

22µH

SW

OUT

MBR0520L

†

D1

5V, 200mA

220µF**

+

10V
TANT

AVX, TPSC107M006R0150

*

AVX, TPSD107M010 R0100

**

†

SUMIDA CD73-220, CD54-220
OR CD43-220. SELECT ACCORDING
TO MAXIMUM LOAD CURRENT

LT1500/01 • TA01

1

LT1500/LT1501

1
2
3
4

8
7
6
5

TOP VIEW

FB/OUT
LBI
LBO
SW

SHDN

V

IN



I

SENSE



GND

S8 PACKAGE

8-LEAD PLASTIC SO

WW

W

U

ABSOLUTE MAXIMUM RATINGS

Supply Voltage ........................................................ 20V

Switch Voltage (SW)................................................ 30V

Shutdown Voltage (SHDN) ...................................... 20V

I

Voltage.......................................................... 20V

SENSE

FB Voltage ................................................................. 5V

LBI Voltage................................................................ 5V

LBO Voltage............................................................. 15V

U

W

PACKAGE/ORDER INFORMATION

TOP VIEW

1

1

SHDN

2

V



C

3

V



IN

4

I



SENSE

5

NC

6

GND

7

PGND


14-LEAD PLASTIC SO

T

JMAX

14
13
12
11
10

9
8

S PACKAGE

= 100°C, θJA = 100°C/W



FB
NFB
SS
LBI
LBO
SYNC
SW

SHDN

2

V



C

3

V



IN

4

I



SENSE

5

NC

6

GND

7

PGND


14-LEAD PLASTIC SO

T

= 100°C, θJA = 100°C/W

JMAX

Operating Ambient Temperature Range

Commercial .............................................0°C to 70°C

Industrial ............................................ –40°C to 85°C

Operating Junction Temperature Range

Commercial ...........................................0°C to 100°C

Industrial .......................................... –40°C to 100°C

Storage Temperature Range................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec)..................300°C

U

TOP VIEW

14

(3.3V/5V)

V

OUT

13

SELECT

12

SS

11

LBI

10

LBO

9

SYNC

8

SW

S PACKAGE



T

= 100°C, θJA = 120°C/W

JMAX

ORDER PART NUMBER ORDER PART NUMBER ORDER PART NUMBER

LT1500CS
LT1500IS

LT1500CS-3/5
LT1500IS-3/5

LT1501CS8
LT1501CS8-3.3
LT1501CS8-5
LT1501IS8
LT1501IS8-3.3
LT1501IS8-5

Consult factory for Military grade parts.

ELECTRICAL CHARACTERISTICS

TJ = 25°C, VIN = 2.3V unless otherwise noted.

PARAMETER CONDITIONS MIN TYP MAX UNITS

Feedback/Output Pin Reference Voltage LT1500/LT1501, T

= 25°C 1.240 1.265 1.290 V

J

All Conditions (Note 6) ● 1.235 1.295 V
LT1500-3/5, Select Pin Open 3.230 3.300 3.370 V

All Conditions (Note 6) ● 3.200 3.400 V
LT1500-3/5, Select Pin Grounded 4.900 5.000 5.100 V

All Conditions (Note 6) ● 4.85 5.15 V
Reference Voltage Line Regulation VIN = 2.3V to 15V ● 0.02 0.06 %/V
Feedback Pin Bias Current ● 30 100 nA

2

LT1500/LT1501

ELECTRICAL CHARACTERISTICS

PARAMETER CONDITIONS MIN TYP MAX UNITS

Internal Divider Current LT1500-3.3/LT1501-3.3

LT1500-5/LT1501-5 ● 33 45 µA
Operating Quiescent Current V

Supply Current in Shutdown V

Shutdown Pin Threshold ● 0.4 1.1 V
Shutdown Pin Input Current V
Input Start-Up Voltage V

Undervoltage Lockout Light Load 1.8 V

Power Switch

Switch On Resistance ISW = 0.7A (Note 2) ● 0.50 0.72 Ω
Peak Switch Current (Note 3) ● 0.7 0.85 1.3 A
Switch Breakdown Voltage ISW = 100µA ● 30 45 V
Switch Leakage Current V

Switch Turn-On Delay (Note 5) 800 ns
Switch Turn-Off Delay (Note 5) 400 ns
Current Sense Resistor ● 0.28 0.42 Ω

Low-Battery Comparator

Low-Battery Threshold Falling Edge ● 1.20 1.24 1.28 V
Threshold Hysteresis 20 mV
LBI Input Bias Current ● 20 50 nA
LBO Output Low State V

LBO Leakage Current V

LT1500 Functions

SYNC Pin Bias Current V
SYNC Pin Threshold ● 0.4 1.3 V
Error Amplifier Transconductance 600 µmho
VC Pin Source Current 20 µA
VC Pin High Clamp Voltage 1.20 1.26 1.32 V
NFB Reference Voltage FB Pin Open ● 1.230 1.265 1.300 V
NFB Pin Bias Current ● 12 20 µA
NFB to FB Transconductance Note 4 10,000 µmho
Soft Start Bias Current Current Flows Out of Pin ● 247 µA

≤ 5V, V

IN

VIN = 15V ● 320 µA

≤ 0.2V, Fixed Voltages (Note 7)

SHDN

≥ 0°C ● 815 µA

T

J

T

< 0°C20µA

J

= 2.3V ● 310 µA

SHDN

= V

SHDN

Full Load 2.0 2.1 V

SW

VSW = 20V ● 0.3 10 µA

LBI

I

SINK

LBI

SYNC

IN

TJ ≥ 0°C ● 2.0 2.1 V
TJ < 0°C 2.2 V

= 5V ● 0.2 5 µA

= 1.2V, I

= 2mA ● 0.3 0.5 V

= 1.3V, V

= 3.3V ● 15 35 µA

TJ = 25°C, VIN = 2.3V unless otherwise noted.

● 22 30 µA

= 2.3V (Note 1) ● 200 280 µA

SHDN

= 100µA ● 0.1 0.25 V

SINK

≤ 15V ● 2 µA

LBO

3

LT1500/LT1501

LOAD CURRENT (mA)

0255075

FREQUENCY (kHz)

1000

100

10

100 125 150 175 200

LTC1500/01 • TPC22

10µH

50µH

20µH

100µH

BURST REGION

VIN = 5V

ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating
temperature range.

Note 1: Feedback pin or output is held sightly above the regulated value to
force the V

node low and switching to stop.

C

Note 2: See Typical Performance Characteristics for graph of Guaranteed
Switch Voltage vs Saturation Voltage.

Note 3: Peak switch current is the guaranteed minimum value of switch
current available in normal operation. Highest calculated switch current at
full load should not exceed the minimum value shown.

Note 4: Loading on FB pin will affect NFB reference voltage. ∆V

= IFB/gm.

NFB

Do not exceed 10µA loading on FB when NFB is being used.
Note 5: This is the delay between sense pin current reaching its upper or

lower threshold and switch transition. Switch delay times cause peak-to-

W

U

peak inductor current to increase and therefore switching frequency to be
low. This effect will be significant for frequencies above 100kHz. See
Application Information and Typical Performance Characteristics.

Note 6: Reference voltage under all conditions includes V
all loads and full temperature range.

Note 7: As with all boost regulators the output voltage of the LT1500
cannot fall to less than input voltage because of the path through the catch
diode. This means that the output voltage divider on adjustable parts will
still be generating feedback voltage at the FB pin (fixed voltage parts have
an internal switch to disconnect the divider in shutdown). If the voltage on
FB is greater than 0.6V in shutdown, the internal error amplifier will draw
current that adds to shutdown current. See graph of Shutdown Current vs
FB voltage in Typical Performance Characteristics.

TYPICAL PERFORMANCE CHARACTERISTICS

Switching Frequency
(3.3V Output)

1000

VIN = 2.3V

100

FREQUENCY (kHz)

10µH

20µH

50µH

100µH

Switching Frequency (5V Output)

1000

VIN = 3V

100

FREQUENCY (kHz)

50µH

100µH

10µH

20µH

= 2.1V to 15V,

IN

Switching Frequency (12V Output)

EFFICIENCY (%)

BURST REGION

10

0 50 100

LOAD CURRENT (mA)

Efficiency (3.3V Output)

100

90

80

70

60

50

40

30

L = 100µH

L = 10µH

TJ = 25°C

= 2.3V

V

IN

LOW LOSS INDUCTOR

1

LOAD CURRENT (mA)

10 100 1000

150 200 250 300

LTC1500/01 • TPC20

L = 33µH

LTC1500/01 • TPC17



BURST REGION

10

0 50 100

LOAD CURRENT (mA)

Efficiency (5V Output)

100

90

80

70

60

EFFICIENCY (%)

50

40

30

L = 100µH

L = 10µH

VIN = 3V
LOW LOSS INDUCTOR

1

10 100 1000

LOAD CURRENT (mA)

150 200 250 300

LTC1500/01 • TPC21

L = 33µH

LTC1500/01 • TPC18



Efficiency (12V Output)

100

90

80

70

60

EFFICIENCY (%)

50

40

30

L = 100µH

L = 10µH

VIN = 5V
LOW LOSS INDUCTOR

1

10 100 1000

LOAD CURRENT (mA)

L = 33µH

LTC1500/01 • TPC19

4

W

I

LOAD

= 50mA

I

LOAD

= 10mA

INPUT VOLTAGE (V)

0

EFFICIENCY (%)

100

90

80

70

60

50

40

2

468

LT1500/01 • TPC13

10 12

TJ = 25°C
L = 33µH
LOW LOSS INDUCTOR

U

TYPICAL PERFORMANCE CHARACTERISTICS

LT1500/LT1501

Efficiency (3.3V Output)

100

90

80

70

EFFICIENCY (%)

60

TJ = 25°C

50

L = 33µH
LOW LOSS INDUCTOR

40

1.75

I

LOAD

2.25 2.50 2.75

2.00
INPUT VOLTAGE (V)

= 100mA

Inductor Copper Loss
(3.3V Output)

10

R = 1Ω

1

I

LOAD

R = 0.5Ω

R = 0.2Ω

R = 0.1Ω

= 10mA

3.00 3.25

LT1500/01 • TPC11

Efficiency (5V Output)

100

I

= 10mA

90

80

70

EFFICIENCY (%)

60

50

40

2.0

LOAD

TJ = 25°C
L = 33µH
LOW LOSS INDUCTOR

3.0 3.5 4.0

2.5
INPUT VOLTAGE (V)

I

LOAD

= 100mA

Inductor Copper Loss (5V Output)

10

VIN = 3V

1

R = 1Ω

R = 0.5Ω

4.5 5.0

LT1500/01 • TPC12

R = 0.2Ω

R = 0.1Ω

Efficiency (12V Output)

Inductor Copper Loss
(12V Output)

10

VIN = 5V

1

R = 1Ω

R = 0.5Ω

R = 0.2Ω

EFFICIENCY LOSS (%)

VIN = 2.3V

0.1
0 50 100

LOAD CURRENT (mA)

Maximum Load Current
(3.3V Output)

600

500

400

300

200

OUTPUT CURRENT (mA)

100

0

1.50

2.00 2.25 2.50

1.75
INPUT VOLTAGE (V)

150 200 250 300

LT1500/01 • TPC14

L ≥ 33µH

L = 10µH

2.75 3.00

LT1500/01 • TPC08

EFFICIENCY LOSS (%)

0.1



600

500

400

300

200

OUTPUT CURRENT (mA)

100

0

0 50 100

150 200 250 300

LOAD CURRENT (mA)

Maximum Load Current
(5V Output)

L ≥ 33µH

L = 10µH

2.0

3.0 3.5 4.0

2.5
INPUT VOLTAGE (V)

LT1500/01 • TPC15

4.5 5.0

LT1500/01 • TPC09

EFFICIENCY LOSS (%)

0.1



600

500

400

300

200

OUTPUT CURRENT (mA)

100

0

0255075

100 125 150 175 200

LOAD CURRENT (mA)

Maximum Load Current
(12V Output)

L = 33µH

L = 100µH

L = 10µH

0

468

2

INPUT VOLTAGE (V)

LTC1500/01 • TPC16

10 12

LT1500/01 • TPC10

5