LINEAR TECHNOLOGY LT1934, LT1934-1 Technical data

LT1934/LT1934-1

BOOST

V

IN

LT1934

SHDN

1934 TA01

C2

2.2μF

0.22μF

10pF

C1: SANYO 4TPB100M
C2: TAIYO YUDEN GMK325BJ225MN
D1: ON SEMICONDUCTOR MBR0540
D2: CENTRAL CMDSH-3
L1: SUMIDA CDRH4D28-470

V

OUT

3.3V
250mA

D2

604k

1M

L1

47μH

D1

V

IN

4.5V TO 34V

ON OFF

SW

FB

GND

C1
100μF

+

LOAD CURRENT (mA)

60

EFFICIENCY (%)

70

80

90

100

0.1 10 100

1934 TA02

50

1

LT1934
V

IN

= 12V

V

OUT

= 5V

V

OUT

= 3.3V

Micropower Step-Down

Switching Regulators

in ThinSOT and DFN

FEATURES

n

Wide Input Voltage Range: 3.2V to 34V

n

Micropower Operation: IQ = 12μA

n

5V at 250mA from 6.5V to 34V Input (LT1934)

n

5V at 60mA from 6.5V to 34V Input (LT1934-1)

n

3.3V at 250mA from 4.5V to 34V Input (LT1934)

n

3.3V at 60mA from 4.5V to 34V Input (LT1934-1)

n

Low Shutdown Current: < 1μA

n

Low V

n

Low Profi le (1mm) SOT-23 (ThinSOTTM) and

Switch: 200mV at 300mA

CESAT

(2mm × 3mm × 0.8mm) 6-Pin DFN Package

APPLICATIONS

n

Wall Transformer Regulation

n

Automotive Battery Regulation

n

Standby Power for Portable Products

n

Distributed Supply Regulation

n

Industrial Control Supplies

DESCRIPTION

The LT®1934 is a micropower step-down DC/DC converter
with internal 400mA power switch, packaged in a low
profi le (1mm) ThinSOT. With its wide input range of 3.2V
to 34V, the LT1934 can regulate a wide variety of power
sources, from 4-cell alkaline batteries and 5V logic rails
to unregulated wall transformers and lead-acid batteries.
Quiescent current is just 12μA and a zero current shut­down mode disconnects the load from the input source,
simplifying power management in battery-powered sys­tems. Burst Mode
power switch result in high effi ciency over a broad range
of load current.

The LT1934 provides up to 300mA of output current. The
LT1934-1 has a lower current limit, allowing optimum
choice of external components when the required output
current is less than 60mA. Fast current limiting protects
the LT1934 and external components against shorted
outputs, even at 34V input.

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.

®

operation and the low drop internal

TYPICAL APPLICATION

3.3V Step-Down Converter

Effi ciency

1934fd

1

LT1934/LT1934-1

ABSOLUTE MAXIMUM RATINGS

Input Voltage (VIN) ................................................... 34V

BOOST Pin Voltage ................................................. 40V

BOOST Pin Above SW Pin ........................................ 20V

SHDN Pin ................................................................. 34V

FB Voltage .................................................................. 6V

SW Voltage ............................................................... V

PIN CONFIGURATION

TOP VIEW

BOOST 1

GND 2

FB 3

S6 PACKAGE

6-LEAD PLASTIC TSOT-23

T

= 125°C, θJA = 250°C/ W, θJC = 102°C/W

JMAX

6 SW

5 V

IN

4 SHDN

(Note 1)

Operating Temperature Range (Note 2)

LT1934E/LT1934E-1 .............................– 40°C to 85°C

LT1934I/LT1934I-1 .............................– 40°C to 125°C

Maximum Junction Temperature .......................... 125°C

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

Lead Temperature (Soldering, 10 sec)

IN

TSOT-23 ............................................................ 300°C

TOP VIEW

6

1

BOOST

SW

2

V

3

IN

6-LEAD (2mm s 3mm) PLASTIC DFN

EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDEDED TO PCB

θJA = 73.5°C/ W, θJC = 12°C/W

7

DCB PACKAGE

FB

5

GND

SHDN

4

ORDER INFORMATION

LEAD FREE FINISH TAPE AND REEL S6 PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LT1934ES6#PBF LT1934ES6#TRPBF LTXP 6-Lead Plastic TSOT-23 –40°C to 85°C

LT1934ES6-1#PBF LT1934ES6-1#TRPBF LTF8 6-Lead Plastic TSOT-23 –40°C to 85°C

LT1934IS6#PBF LT1934IS6#TRPBF LTAJB 6-Lead Plastic TSOT-23 –40°C to 85°C

LT1934IS6-1#PBF LT1934IS6-1#TRPBF LTAJC 6-Lead Plastic TSOT-23 –40°C to 85°C

LT1934IDCB#PBF LT1934IDCB#TRPBF LCFZ

LT1934EDCB#PBF LT1934EDCB#TRPBF LCFZ

LT1934IDCB-1#PBF LT1934IDCB-1#TRPBF LDHC

LT1934EDCB-1#PBF LT1934EDCB-1#TRPBF LDHC

LEAD BASED FINISH TAPE AND REEL S6 PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LT1934ES6 LT1934ES6#TR LTXP 6-Lead Plastic TSOT-23 –40°C to 85°C

LT1934ES6-1 LT1934ES6-1#TR LTF8 6-Lead Plastic TSOT-23 –40°C to 85°C

LT1934IS6 LT1934IS6#TR LTAJB 6-Lead Plastic TSOT-23 –40°C to 85°C

LT1934IS6-1 LT1934IS6-1#TR LTAJC 6-Lead Plastic TSOT-23 –40°C to 85°C

LT1934IDCB LT1934IDCB#TR LCFZ

LT1934EDCB LT1934EDCB#TR LCFZ

LT1934IDCB-1 LT1934IDCB-1#TR LDHC

LT1934EDCB-1 LT1934EDCB-1#TR LDHC

Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/

This product is only offered in trays. For more information go to: http://www.linear.com/packaging/

6-Lead (2mm × 3mm) Plastic DFN

6-Lead (2mm × 3mm) Plastic DFN

6-Lead (2mm × 3mm) Plastic DFN

6-Lead (2mm × 3mm) Plastic DFN

6-Lead (2mm × 3mm) Plastic DFN

6-Lead (2mm × 3mm) Plastic DFN

6-Lead (2mm × 3mm) Plastic DFN

6-Lead (2mm × 3mm) Plastic DFN

–40°C to 125°C

–40°C to 125°C

–40°C to 125°C

–40°C to 125°C

–40°C to 125°C

–40°C to 125°C

–40°C to 125°C

–40°C to 125°C

1934fd

2

LT1934/LT1934-1

ELECTRICAL CHARACTERISTICS

The ● denotes specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T

= 25°C. VIN = 10V, V

A

SYMBOL CONDITIONS MIN TYP MAX UNITS

Undervoltage Lockout

–40°C ≤ T
–40°C ≤ T

Quiescent Current V

= 1.3V

FB

–40°C ≤ T
–40°C ≤ T

V

= 0V 0.01 2 μA

SHDN

FB Comparator Trip Voltage V

Falling –40°C ≤ TA ≤ 85°C

FB

–40°C ≤ T

FB Comparator Hysteresis 10 mV

FB Pin Bias Current VFB = 1.25V –40°C ≤ TA ≤ 85°C

–40°C ≤ T

FB Voltage Line Regulation 4V < V

Switch Off Time V

Maximum Duty Cycle V

< 34V 0.007 %/V

IN

> 1V

FB

V

= 0V

FB

= 1V –40°C ≤ TA ≤ 85°C

FB

–40°C ≤ T

Switch V

CESAT

ISW = 300mA (LT1934, S6 Package)
I

= 300mA (LT1934, DCB Package)

SW

I

= 75mA (LT1934-1, S6 Package)

SW

I

= 75mA (LT1934-1, DCB Package)

SW

Switch Current Limit LT1934

LT1934-1

BOOST Pin Current ISW = 300mA (LT1934)

I

= 75mA (LT1934-1)

SW

Minimum Boost Voltage (Note 3) I

= 300mA (LT1934)

SW

I

= 75mA (LT1934-1)

SW

Switch Leakage Current 2μA

SHDN Pin Current V

SHDN

V

SHDN

= 2.3V
= 34V

SHDN Input Voltage High 2.3 V
SHDN Input Voltage Low 0.25 V

= 15V, unless otherwise noted.

BOOST

≤ 85°C

A

≤ 125°C

A

≤ 85°C

A

≤ 125°C

A

l
l

l
l

l

≤ 125°C

A

l

l

≤ 125°C

A

l

l

≤ 125°C

A

l

1.22

1.21

1.25

1.25

1.4 1.8

85
83

350

90

3
3
3

12
12
12

2
2

12

88
88

200
225

65
70

400
120

8.5

6.0

1.8

1.7

0.5

1.5 5

3.2

3.6

3.6

22
26
26

1.27

1.27

±15
±60

2.3 μs

300

120

490
160

12
10

2.5

2.5

V
V
V

μA
μA
μA

V
V

nA
nA

μs

%
%

mV
mV
mV
mV

mA
mA

mA
mA

V
V

μA
μA

Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.

Note 2: The LT1934E and LT1934E-1 are guaranteed to meet performance
specifi cations from 0°C to 85°C. Specifi cations over the –40°C to 85°C

operating temperature range are assured by design, characterization and
correlation with statistical process controls. The LT1934I and LT1934I-1
specifi cations are guaranteed over the –40°C to 125°C temperature range.

Note 3: This is the minimum voltage across the boost capacitor needed to
guarantee full saturation of the internal power switch.

1934fd

3

LT1934/LT1934-1

TYPICAL PERFORMANCE CHARACTERISTICS

LT1934 Effi ciency, V

100

LT1934

= 5V

V

OUT

L = 47μH

90

= 25°C

T

A

80

70

EFFICIENCY (%)

60

50

0.1 10 100

VIN = 12V

VIN = 24V

1

LOAD CURRENT (mA)

LT1934-1 Effi ciency, V

100

LT1934-1

= 3.3V

V

OUT

L = 100μH

90

= 25°C

T

A

80

70

EFFICIENCY (%)

60

VIN = 12V

= 5V LT1934 Effi ciency, V

OUT

1934 G01

= 3.3V Current Limit vs Temperature Off Time vs Temperature

OUT

VIN = 24V

100

LT1934

= 3.3V

V

OUT

L = 47μH

90

= 25°C

T

A

80

70

EFFICIENCY (%)

60

50

0.1 10 100

500

400

300

200

100

SWITCH CURRENT LIMIT (mA)

VIN = 12V

1

LOAD CURRENT (mA)

LT1934

LT1934-1

= 3.3V LT1934-1 Effi ciency, V

OUT

VIN = 5V

VIN = 24V

1934 G02

100

LT1934-1
V

OUT

L = 150μH

90

= 25°C

T

A

80

70

EFFICIENCY (%)

60

50

0.1

3.0

2.5

2.0

1.5

OFF TIME (μs)

1.0

0.5

= 5V

1 10 100

LOAD CURRENT (mA)

OUT

VIN = 12V

VIN = 24V

= 5V

1934 G03

50

0.1

1 10 100

LOAD CURRENT (mA)

1934 G04

0

–50 –25

Frequency Foldback VFB vs Temperature

16

TA = 25oC

14

12

10

8

6

SWITCH OFF TIME (μs)

4

2

0

0.2 0.4 0.8

0

FEEDBACK PIN VOLTAGE (V)

0.6

1.0

1.2

1934 G07

1.27

1.26

1.25

1.24

FEEDBACK VOLTAGE (V)

1.23

1.22
–50 –25

4

50

25

0

TEMPERATURE (°C)

50

25

0

TEMPERATURE (°C)

0

–50

100

125

1934 G05

75

–25 0

TEMPERATURE (°C)

50 100 125

25 75

1934 G06

SHDN Bias Current
vs SHDN Voltage

2.0
TA = 25°C

1.5

1.0

0.5

SHDN PIN CURRENT (μA)

0

0

100

125

1934 G08

75

2468

SHDN PIN VOLTAGE (V)

10 12

1934 G09

1934fd

TYPICAL PERFORMANCE CHARACTERISTICS

LT1934/LT1934-1

Quiescent Current
vs Temperature

20

15

10

5

QUIESCENT CURRENT (μA)

0

–50

–25 0 25 50

TEMPERATURE (°C)

75 100 125

1934 G10

Undervoltage Lockout
vs Temperature

4.0

3.5

3.0

UVLO (V)

2.5

2.0
–50

–25 0 25 50

TEMPERATURE (°C)

Minimum Input Voltage
V

= 5V

OUT

8

LT1934

= 5V

V

OUT

= 25°C

T

A

BOOST DIODE TIED TO OUTPUT

7

VIN TO START

75 100 125

1934 G11

Minimum Input Voltage
V

= 3.3V

OUT

6.0
LT1934

= 3.3V

V

OUT

= 25°C

T

5.5

A

BOOST DIODE TIED TO OUTPUT

5.0

4.5

4.0

INPUT VOLTAGE (V)

3.5

3.0

VIN TO START

VIN TO RUN

0.1 10 100

1

LOAD CURRENT (mA)

1934 G12

6

VIN TO RUN

0.1 10 100

1

LOAD CURRENT (mA)

PIN FUNCTIONS

(TSOT-23/DFN)

INPUT VOLTAGE (V)

5

4

BOOST (Pin 1/Pin 1): The BOOST pin is used to provide a
drive voltage, higher than the input voltage, to the internal
bipolar NPN power switch.

GND (Pin 2/Pin 5): Tie the GND pin to a local ground plane
below the LT1934 and the circuit components. Return the
feedback divider to this pin.

FB (Pin 3/Pin 6): The LT1934 regulates its feedback pin
to 1.25V. Connect the feedback resistor divider tap to this
pin. Set the output voltage according to V
+ R1/R2) or R1 = R2 (V

/1.25 – 1).

OUT

= 1.25V (1

OUT

SHDN (Pin 4/Pin 4): The SHDN pin is used to put the LT1934

1934 G13

in shutdown mode. Tie to ground to shut down the LT1934.
Apply 2.3V or more for normal operation. If the shutdown
feature is not used, tie this pin to the V

VIN (Pin 5/Pin 3): The V

pin supplies current to the

IN

IN

pin.

LT1934’s internal regulator and to the internal power
switch. This pin must be locally bypassed.

SW (Pin 6/Pin 2): The SW pin is the output of the internal
power switch. Connect this pin to the inductor, catch diode
and boost capacitor.

Exposed Pad (Pin 7, DFN Package): This pin must be
soldered to ground plane.

1934fd

5

LT1934/LT1934-1

BLOCK DIAGRAM

V

V

IN

IN

C2

+

+

–

BOOST

D2

ON OFF

SHDN

V

GND

REF

12μs DELAY

1.8μs DELAY

1.25V

ON TIME

OFF TIME

R2 R1

RSQa

Q

SW

C3

L1

D1

V

OUT

C1

+

ENABLE

–

FEEDBACK
COMPARATOR

FB

1934 BD

6

1934fd