Linear Technology LTC1266-5, LTC1266-3.3, LTC1266 Datasheet

LTC1266

LOAD CURRENT (A)

0.01

80

EFFICIENCY (%)

85

90

95

100

0.1 51

LTC1266 • TA02

VIN = 5V

LTC1266-3.3/LTC1266-5

Synchronous Regulator

Controller for

N- or P-Channel MOSFETs

EATU

F

■

Ultra-High Efficiency: Over 95% Possible

■

Drives N-Channel MOSFET for High Current or

RE

S

P-Channel MOSFET for Low Dropout

■

Pin Selectable Burst Mode Operation

■

1% Output Accuracy (LTC1266A)

■

Pin Selectable Phase of Topside Driver for Boost
or Step-Down Operation

■

Wide VIN Range: 3.5V to 20V

■

On-Chip Low-Battery Detector

■

High Efficiency Maintained over Large Current Range

■

Low 170µA Standby Current at Light Loads

■

Current Mode Operation for Excellent Line and Load
Transient Response

■

Logic Controlled Micropower Shutdown: IQ < 40µA

■

Short Circuit Protection

■

Synchronous Switching with Nonoverlaping Gate Drives

■

Available in 16-Pin Narrow SO Package

U

O

PPLICATI

A

■

Notebook and Palmtop Computers

■

Portable Instruments

■

Cellular Telephones

■

DC Power Distribution Systems

■

GPS Systems

S

DUESCRIPTIO

The LTC®1266 series is a family of synchronous switching
regulator controllers featuring automatic Burst Mode
operation to maintain high efficiencies at low output
currents. These devices drive external power MOSFETs at
switching frequencies up to 400kHz using a constant off­time current mode architecture providing constant ripple
current in the inductor. They can drive either an N-channel
or a P-channel topside MOSFET.

The operating current level is user-programmable via an
external current sense resistor. Wide input supply range
allows operation from 3.5V to 18V (20V maximum).
Constant off-time architecture provides low dropout regu­lation limited only by the R

of the topside MOSFET

DS(ON)

(when using the P-channel) and the resistance of the
inductor and current sense resistor.

The LTC1266 series combines synchronous switching for
maximum efficiency at high currents with an automatic
low current operating mode, called Burst Mode operation,
which reduces switching losses. Standby power is re­duced to only 1mW at VIN = 5V (at I

= 0). Load currents

OUT

in Burst Mode operation are typically 0mA to 500mA.

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

Burst Mode is a trademark of Linear Technology Corporation.

TM

*COILTRONICS CTXO212801

V

IN

4V TO 9V

+

LOW BAT IN

0V = NORMAL

>1.5V = SHUTDOWN

RC
470Ω

CC
3300pF

U

O

A

PPLICATITYPICAL

MBR0530T1

CIN
100µF
×2

CT
180pF

VIN PWR V

LB

IN

PINV

LTC1266-3.3

SHDN
I

TH

C

T

SGND

LB

OUT

TDRIVE

SENSE

SENSE

BDRIVEBINH
PGND

IN

N-CHANNEL
Si9410

+

1000pF

–

N-CHANNEL
Si9410

Figure 1. High Efficiency Step-Down Converter

D2

LOW BAT OUT

CB

0.1µF

L*
5µH

D1
MBRS130LT3

LTC1266 • TA01

100k

R

SENSE

0.02Ω

V



OUT

3.3V
5A

+

C



OUT

330µF
× 2

LTC1266-3.3 Efficiency

1

LTC1266
LTC1266 - 3. 3/LTC1266 -5

W

O

A

LUTEXI T

S

Input Supply Voltage (Pins 2, 5)............... 20V to – 0.3V

Continuous Output Current (Pins 1, 16) .............. 50mA

Sense Voltages (Pins 8, 9)........................ 13V to – 0.3V

PINV, BINH, SHDN, LB

(Pins 3, 4, 11, 13) .................................20V to – 0.3V

LB

Output Current ........................................... 12mA

OUT

Operating Ambient Temperature Range ...... 0°C to 70°C

Extended Commercial

Temperature Range ........................... –40°C to 85°C

Junction Temperature (Note 1)............................ 125°C

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

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

LECTRICAL C CHARA TERIST

E

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

FB

I

FB

V

OUT

∆V

I

Q1

I

Q2

V

SENSE 1

OUT

Feedback Voltage VIN = 9V, I

LTC1266ACS Topside Switch = N-Ch
LTC1266CS

Feedback Current (LTC1266 Only) ● 0.2 1 µA
Regulated Output Voltage VIN = 9V, I

LTC1266CS-3.3 Topside Switch = N-Ch, V

LTC1266CS-5
Output Ripple (Burst Mode Operation) I
Output Voltage Line Regulation I

Output Voltage Load Regulation 5mA < I

LTC1266-3.3 Burst Mode Operation Enabled, V

LTC1266-3.3 Burst Mode Operation Inhibited, V

LTC1266-5 Burst Mode Operation Enabled, V

LTC1266-5 Burst Mode Operation Inhibited, V
VIN Pin DC Supply Current (Note 2)

Normal Mode 3.5V < V

Sleep Mode 3.5V < V

Shutdown V
PWR VIN DC Supply Current (Note 2)

Normal Mode 3.5V < PWR V

Sleep Mode 3.5V < PWR V

Shutdown V
Current Sense Threshold V

(Burst Mode Operation Enabled)

LTC1266 V

LTC1266-3.3 V

LTC1266-5 V

A

IN

WUW

U

/

TOP VIEW

S PACKAGE

= 125°C, θ

SHDN

O

RDER I FOR ATIO

BDRIVE

16

PGND

15

LB



14

OUT

LB



13

IN

SGND

12

SHDN

11

V

(NC*)

10

FB

+

SENSE

9

= 110°C/W

JA

= V

= 0V unless otherwise noted.

BINH

● 1.275 V

● 1.210 1.25 1.290 V

● 4.90 5.05 5.20 V

LTC1266CS
LTC1266CS-3.3
LTC1266CS-5
LTC1266ACS

ARB

LOAD

LOAD

SHDN

SHDN

BINH

G

S

I

ICS

= 150mA 50 mV
= 50mA

V

PINV

V

PINV

= 2.1V, 3.5V < VIN < 18V 25 50 µA

= 2.1V, 3.5V < PWR VIN < 18V 1 5 µA

= 0V

SENSE

V

SENSE
SENSE

V

SENSE
SENSE

V

SENSE

TA = 25°C, VIN = 10V, V

= 700mA, V

LOAD

= 700mA, V

LOAD

= 0V, Topside Switch = P-Ch, VIN = 7V to 12V –40 0 40 mV
= V

, Topside Switch = N-Ch, VIN = 7V to 12V –40 0 40 mV

PWR

< 2A, R

LOAD

< 18V 2.1 3.0 mA

IN

< 18V 170 250 µA

IN

< 18V 20 40 µA

IN

< 18V 1 5 µA

IN

–

= 3.3V, VFB = V

–

= 3.3V, VFB = V

–

= V

+ 100mV (Forced) 25 mV

OUT

–

= V

– 100mV (Forced) ● 135 155 175 mV

OUT

–

= V

+ 100mV (Forced) 25 mV

OUT

–

= V

– 100mV (Forced) ● 135 155 175 mV

OUT

PACKAGE

TDRIVE

1



PWR V

Consult factory for Industrial and Military grade parts.

= V

PINV

= V

PINV

= 14V ● 3.23 3.33 3.43 V

PWR

= 0.05Ω

SENSE

/2.64 + 25mV (Forced) 25 mV

OUT

/2.64 – 25mV (Forced) ● 135 155 175 mV

OUT

2

IN

PINV

3

BINH

4

V



5

IN

C



6

T

I



7

TH

–

SENSE

8

16-LEAD PLASTIC SO

*FIXED OUTPUT VERSIONS

T

JMAX

,

PWR

,

PWR

= 0V ● 40 65 mV

BINH

= 2V ● 15 25 mV

BINH

= 0V ● 60 100 mV

BINH

= 2V ● 25 40 mV

BINH

WU

ORDER PART

NUMBER

P-P

U

2

LTC1266

LTC1266-3.3/LTC1266 -5

LECTRICAL C CHARA TERIST

E

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

SENSE 2

V

SHDN

I

SHDN

I

PINV

V

BINH

I

BINH

I

CT

t

OFF

t

MAX

tr, t
V

CLAMP

V

LBTRIP

I

LBLEAK

I

LBSINK

I

LBIN

Current Sense Threshold V
(Burst Mode Operation Disabled)

LTC1266 V

LTC1266-3.3 V

LTC1266-5 V

Shutdown Pin Threshold 0.6 0.8 2 V
Shutdown Pin Input Current 0V < V
Phase Invert Pin Input Current 0V < V
Burst Mode Operation 0.8 1.2 2 V

Inhibit Pin Threshold
Burst Mode Operation 0V < V

Inhibit Pin Input Current
CT Pin Discharge Current V

Off-Time (Note 3) CT = 390pF, I
Max On-Time V
Driver Output Transition Times CL = 3000pF (Pins 1, 16), VIN = 6V 100 200 ns

f

Output Voltage Clamp in V
Burst Mode Operation Inhibit

LTC1266 Measured at V

LTC1266-3.3 Measured at V

LTC1266-5 Measured at V
Low-Battery Trip Point VIN = 5V 1.14 1.25 1.35 V

Max Leakage Current into Pin 14 V
Max Sink Current into Pin 14 V
Max Leakage Current into Pin 13 V

ICS

= 2.1V

BINH

SENSE

V

SENSE
SENSE

V

SENSE
SENSE

V

SENSE

SENSE

V

= 0V 2 10 µA

OUT

= 0V, VIN = 18V 60 µs

OUT

= 2.1V

BINH

= 12V 1.17 1.30 1.42 V

V

IN

LBOUT

LBOUT

= 18V 0.2 1 µA

LBIN

TA = 25°C, VIN = 10V, V

–

= 3.3V, VFB = V

–

= 3.3V, VFB = V

–

= V

+ 100mV (Forced) –20 mV

OUT

–

= V

– 100mV (Forced) ● 135 155 175 mV

OUT

–

= V

+ 100mV (Forced) –20 mV

OUT

–

= V

– 100mV (Forced) ● 135 155 175 mV

OUT

< 8V, VIN = 16V 1.2 5 µA

SHDN

< 18V, VIN = 18V 0.2 1 µA

PINV

< 18V, VIN = 18V 0.2 1 µA

BINH

+

= V

– 100mV, V

OUT

= 700mA 4 5 6 µs

LOAD

FB
SENSE
SENSE

= 18V, V
= 1V, V

= 2V 25 200 nA

LBIN

= 0V, 2.5V < VIN < 18V 1 8 mA

LBIN

/2.64 + 25mV (Forced) – 20 mV

OUT

/2.64 – 25mV (Forced) ● 135 155 175 mV

OUT

–

= V

SENSE

–
–

OUT

= V

SHDN

= 0V unless otherwise noted.

BINH

– 300mV 50 70 90 µA

1.30 V

3.43

5.20 V

V

–40°C < TA < 85°C (Note 4), VIN = 10V, unless otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

FB

V

OUT

Feedback Voltage (LTC1266 only) VIN = 9V, I
Regulated Output Voltage VIN = 9V, I

= 700mA 1.21 1.25 1.29 V

LOAD

= 700mA

LOAD

LTC1266-3.3 3.23 3.33 3.43 V

LTC1266-5 4.90 5.05 5.20 V

I

Q1

I

Q2

VIN Pin DC Supply Current (Note 2)

Normal Mode 3.5V < V

Sleep Mode 3.5V < V

Shutdown V

IN
IN

SHUTDOWN

PWR VIN DC Supply Current (Note 2)

Normal Mode 3.5V < PWR V

Sleep Mode 3.5V < PWR V

Shutdown V

SHUTDOWN

< 18V 2.1 3.3 mA
< 18V 170 260 µA

= 2.1V, 3.5V < VIN < 18V 25 60 µA

< 18V 20 50 µA

IN

< 18V 1 7 µA

IN

= 2.1V, 3.5V < PWR VIN < 18V 1 7 µA

3

LTC1266
LTC1266 - 3. 3/LTC1266 -5

LECTRICAL C CHARA TERIST

E

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

SENSE1

Sense 2 Current Sense Threshold V

V

SHDN

t

OFF

Current Sense Threshold V

(Burst Mode Operation Enabled)

LTC1266 V

LTC1266-3.3, LTC1266-5 V

(Burst Mode Operation Disabled)

LTC1266 V

LTC1266-3.3, LTC1266-5 V

Shutdown Pin Threshold 0.55 0.8 2 V
Off-Time (Note 3) CT = 390pF, I

BINH

SENSE

V

SENSE
SENSE

V

SENSE

BINH

SENSE

V

SENSE
SENSE

V

SENSE

= 0V

= 2.1V

ICS

–

= 3.3V, VFB = V

–

= 3.3V, VFB = V

–

= V

+ 100mV (Forced) 25 mV

OUT

–

= V

– 100mV (Forced) 135 155 180 mV

OUT

–

3.3V, VFB = V

–

3.3V, VFB = V

–

= V

+ 100mV (Forced) –20 mV

OUT

–

= V

– 100mV (Forced) 130 155 185 mV

OUT

= 700mA 3.8 5 6.5 µs

LOAD

/2.64 + 25mV (Forced) 25 mV

OUT

/2.64 – 25mV (Forced) 135 155 180 mV

OUT

/2.64 + 25mV (Forced) –20 mV

OUT

/2.64 – 25mV (Forced) 130 155 185 mV

OUT

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

Note 1: T
dissipation P

is calculated from the ambient temperature TA and power

J

according to the following formula:

D

TJ = TA + (PD × 110°C/W)

Note 2: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.

UW

LPER

Efficiency vs Input Voltage

100

FIGURE 1 CIRCUIT

95

90

I

= 5A

LOAD

85

EFFICIENCY (%)

80

75

70

3

567

4

INPUT VOLTAGE (V)

F

I

LOAD

R

O

I

LOAD

= 100mA

ATYPICA

= 2.5A

89

LTC1266 • TPC01

CCHARA TERIST

E

C

Line Regulation Load Regulation

40

FIGURE 1 CIRCUIT

= 1A

I

LOAD

30

20

10

(mV)

0

OUT

∆V

–10

–20

–30

–40

45678

3

Note 3: In applications where R

is placed at ground potential, the off-

SENSE

time increases approximately 40%.
Note 4: The LTC1266, LTC1266-3.3, and LTC1266-5 are not tested and

not quality assurance sampled at –40°C and 85°C. These specifications
are guaranteed by design and/or correlation.

Note 5: Unless otherwise noted the specifications for the LTC1266A are
the same as those for the LTC1266.

ICS

20

FIGURE 1 CIRCUIT

INPUT VOLTAGE (V)

LTC1266 • TPC02

10

0

–10

(mV)

OUT

–20

∆V

–30

–40

–50

9

0

VIN = 9V (Burst Mode 
OPERATION ENABLED)

VIN = 5V

VIN = 5V (Burst Mode 

OPERATION INHIBITED)



1

2

LOAD CURRENT (A)







3

4

LTC1266 • TPC03

5

4

LPER

LOAD CURRENT (A)

0

–40

∆V

OUT

(mV)

–30

–20

–10

30

10

0.5

1.0

20

0

1.5

2.0 2.5

3.0

LTC1266 • TPC06

FIGURE 11 CIRCUIT

V

IN

= 12V (Burst Mode 

OPERATION ENABLED)

VIN = 5V



VIN = 5V (Burst Mode
OPERATION INHIBITED)

INPUT VOLTAGE (V)

0

SUPPLY CURRENT (µA)

30

40

50

LTC1266 • TPC09

20

10

0

5

10

15

20

V

IN

PWR V

IN

TEMPERATURE (°C)

0

SENSE VOLTAGE (mV)

100

150

200

80

LTC1266 • TPC12

50

0

–50

20

40

60

100

MAX THRESHOLD

MIN THRESHOLD (Burst Mode 

OPERATION INHIBIT)

MIN THRESHOLD (Burst Mode 

OPERATION ENABLED)

F

O

R

ATYPICA

UW

CCHARA TERIST

E

C

LTC1266

LTC1266-3.3/LTC1266 -5

ICS

100

95

90

85

EFFICIENCY (%)

80

75

70

3.0

2.5

2.0

1.5

1.0

SUPPLY CURRENT (mA)

0.5

100

80

60

40

OFF-TIME (µs)

20

Efficiency vs Input Voltage

FIGURE 11 CIRCUIT

I

= 1A

LOAD

I

= 100mA

LOAD

4

0

INPUT VOLTAGE (V)

12

8

VIN DC Supply Current

ACTIVE MODE

SLEEP MODE

0

4

0

INPUT VOLTAGE (V)

12

8

Off-Time vs Output Voltage

V

LTC1266-3.3

0

01

OUTPUT VOLTAGE (V)

LTC1266-5

2

34

I

LOAD

SENSE

LTC1266 • TPC10

= 2.5A

16

LTC1266 • TPC04

16

LTC1266 • TPC07

–

= V

OUT

Line Regulation

40

FIGURE 11 CIRCUIT

= 1A

I

LOAD

30

20

10

(mV)

0

OUT

∆V

–10

–20

–30

20

–40

0

812

4

INPUT VOLTAGE (V)

16

LTC1266 • TPC05

Power VIN DC Supply Current

25

20

V

OUT

ACTIVE MODE

SLEEP MODE

4

INPUT VOLTAGE (V)

OUT

= 3.3V

2

4

(VIN – V

8

) Voltage

0°C

25°C

6

) VOLTAGE (V)

OUT

12

16

20

LTC1266 • TPC08

70°C

12108

14

LTC1266 • TPC11

16

15

10

SUPPLY CURRENT (µA)

5

20

0

0

Operating Frequency
vs (VIN – V

3.0


2.5

2.0

1.5

1.0

NORMALIZED FREQUENCY

0.5

5

0

0

Load Regulation

Supply Current in Shutdown

Current Sense Threshold Voltage

5

LTC1266
LTC1266 - 3. 3/LTC1266 -5

U

UU

PI FU CTIO S

TDrive (Pin 1): High Current Drive for Topside MOSFET.
This MOSFET can be either P-channel or N-channel, user
selectable by Pin 3. Voltage swing at this pin is from PWR
VIN to ground.

PWR VIN (Pin 2): Power Suppy for Drive Signals. Must be
closely decoupled to power ground (Pin 15).

PINV (Pin 3): Phase Invert. Sets the phase of the topside
driver to drive either a P-channel or an N-channel MOSFET
as follows:

P-channel: Pin 3 = 0V
N-channel: Pin 3 = PWR V

BINH (Pin 4): Burst Mode Operation Inhibit. A CMOS logic
high on this pin will disable the Burst Mode operation
feature forcing continuous operation down to zero load.

VIN (Pin 5): Main Supply Pin.
CT (Pin 6): External Capacitor. CT from Pin 4 to ground sets

the operating frequency. The actual frequency is also
dependent on the input voltage.

ITH (Pin 7): Gain Amplifier Decoupling Point. The current
comparator threshold increases with the Pin 7 voltage.

Sense– (Pin 8): Connects to internal resistive divider
which sets the output voltage in LTC1266-3.3 and
LTC1266-5 versions. Pin 8 is also the (–) input for the
current comparator.

IN

Sense+ (Pin 9): The (+) Input to the Current Comparator.
A built-in offset between Pins 8 and 9 in conjunction with
R

VFB (Pin 10): For the LTC1266 adjustable version, Pin 10
serves as the feedback pin from an external resistive
divider used to set the output voltage. On LTC1266-3.3
and LTC1266-5 versions this pin is not used.

SHDN (Pin 11): When grounded, the LTC1266 series
operates normally. Pulling Pin 11 high holds both MOSFETs
off and puts the LTC1266 in micropower shutdown mode.
Requires CMOS logic signal with tr, tf < 1µ s. Should not be
left floating.

SGND (Pin 12): Small-Signal Ground. Must be routed
separately from other grounds to the (–) terminal of C

LBIN (Pin 13): Input to the Low-Battery Comparator. This
input is compared to an internal 1.25V reference.

LB

Comparator. This pin will sink current when Pin 13 is
below 1.25V.

PGND (Pin 15): Driver Power Ground. Connects to source
of N-channel MOSFET and the (–) terminal of CIN.

BDrive (Pin 16): High Current Drive for Bottom N-Chan­nel MOSFET. Voltage swing at Pin 16 is from ground to
PWR VIN.

sets the current trip threshold.

SENSE

(Pin 14): Open Drain Output of the Low-Battery

OUT

OUT

.

6