ST STBB1PUR User Manual

dual mode buck-boost DC-DC converter

Features

■ Buck-boost DC-DC converter

■ Operating input voltage range from 2.0 V to 5.5

V

■ 2% DC feedback voltage tolerance

■ Synchronous rectification

■ Shutdown function

■ 1.5 MHz switching frequency

■ Power save mode at light load

■ Typical efficiency: > 94 %

■ 1 A output current capability

■ Shutdown current < 1 µA

■ Available in DFN10 (3 x 3 mm)

Applications

■ Single cell Li-Ion and 3 cells alkaline, Ni-MH

powered devices

■ SD/MMC memory card supply

■ Palmtop computers

■ Cell phones

■ Digital cameras

STBB1XX

1 A, high efficiency single inductor

DFN10 (3 x 3 mm)

integrated low-R
MOSFET switches contribute to its high efficiency.
The MODE pin allows selecting between auto
mode and forced PWM mode thus taking benefit
either of lower power consumption or best
dynamic performance. The device includes also
soft-start control, thermal shutdown and current
limit. The STBB1 is packaged in DFN10 (3 x 3
mm).

N-channel and P-channel

DSon

Description

The STBB1 is a fixed frequency, high efficiency,
buck-boost DC-DC converter able to provide
output voltages ranging from 1.2 V to 5.5 V and
input voltages from 2.0 V to 5.5 V. The device can
operate with input voltages higher than, equal to,
or lower than the output voltage making the
product suitable for single lithium-Ion, multicell
alkaline or NiMH applications where the output
voltage is within the battery voltage range. The

Table 1. Device summary

Order code Marking Output voltage

STBB1PUR BB1 ADJ

September 2010 Doc ID 15474 Rev 5 1/21

www.st.com

21

Contents STBB1XX

Contents

1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

6 Detailed description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

6.1 General description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

6.2 Dual mode operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

6.3 External synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

6.4 Enable pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

6.5 Protection features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

6.5.1 Soft-start and short-circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

6.5.2 Under-voltage lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

6.5.3 Over-temperature protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

7 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

8 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

8.1 Programming the output voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

8.2 Inductor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

8.3 Input and output capacitor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

9 Recommended PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

10 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

11 Different output voltage versions of the STBB1 available on request 19

12 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2/21 Doc ID 15474 Rev 5

STBB1XX Block diagram

1 Block diagram

Figure 1. STBB1 block diagram

V

V

VINA

VINA

MODE/SYNC

MODE/SYNC

EN

EN

V

SW1 SW2

IN

IN

Current

Current

sensor

GND

GND

sensor

Modulator

Modulator

Temp.

Temp.

Control

Control

Oscillator

Oscillator

DEVICE

DEVICE

CONTROL

CONTROL

SW1 SW2

Gate

Gate

Control

Control

V

V

REF

REF

V

OUT

OUT

FB

FB

PGND

PGND

Doc ID 15474 Rev 5 3/21

Absolute maximum ratings STBB1XX

2 Absolute maximum ratings

Table 2. Absolute maximum ratings

Symbol Parameter Value Unit

VINA, VIN Input voltage - 0.3 to 7 V

VOUT Output voltage - 0.3 to 7 V

SW1, SW2 DC voltage - 0.3 to 7 V

FB DC voltage - 0.3 to 1.5 V

MOD/SYNC, EN DC voltage - 0.3 to 7 V

T

J

T

STG

T

JOP

ESD Human body model 2 kV

Maximum junction temperature 150 °C

Storage temperature range - 65 to + 150 °C

Operating junction temperature range - 40 to + 85 °C

Note: Absolute maximum ratings are those values beyond which damage to the device may occur.

Functional operation under these conditions is not implied.

Table 3. Thermal data

Symbol Parameter Value Unit

R

R

thJC

thJA

Thermal resistance junction-case 2.96 °C/W

Thermal resistance junction-ambient 30.9 °C/W

4/21 Doc ID 15474 Rev 5

STBB1XX Pin configuration

3 Pin configuration

Figure 2. Pin connections (top through view)

Table 4. Pin description

Pin n° Symbol Name and function

1 VOUT Output voltage

2SW2

3 PGND Power ground

4SW1

5VIN

6EN

7

8 VINA Supply voltage for control stage

9 GND Signal ground

10 FB Feedback voltage

MODE

(SYNC)

Exposed pad Power ground

Switch pin - Internal switches are connected to this pin. Connect inductor
between SW1 to SW2

Switch pin - Internal switches are connected to this pin. Connect inductor
between SW1 and SW2

Power input voltage. Connect a ceramic bypass capacitor (10 µF minimum)
between this pin and PGND

Enable pin. Connect this pin to GND or a voltage lower than 0.4 V to shut down
the IC. A voltage higher than 1.2 V is required to enable the IC.

Operation mode selection.
If MODE pin is low, the STBB1 automatically switches between pulse skipping
and fixed frequency PWM according to the load level.
If MODE pin is pulled high, the STBB1 works always in PWM mode.
When a square waveform is applied, this pin provides the clock signal for
oscillator synchronization

Doc ID 15474 Rev 5 5/21

Typical application STBB1XX

4 Typical application

Figure 3. Application circuit - adjustable output version

VIN

VIN

CIN

CIN

Figure 4. Application circuit - fixed output version

VIN

VIN

VINA

VINA

EN

EN

MODE/SYN

MODE/SYN

L

L

SW1 SW2

SW1 SW2

STBB1PUR

STBB1PUR

GND PGND

GND PGND

L

L

VOUT

VOUT

FB

FB

VOUT

VOUT

COUT

R1

R1

COUT

R2

R2

SW1 SW2

VIN

VIN

CIN

CIN

Table 5. List of external components

SW1 SW2

VIN

VIN

VINA

VINA

STBB1PUR33

STBB1PUR33

EN

EN

MODE/SYN

MODE/SYN

GND PGND

GND PGND

(1)

VOUT

VOUT

FB

FB

VOUT

VOUT

COUT

COUT

Component Manufacturer Part number Value Size

CIN Murata GRM188R60J106ME47D 10 µF 0603

COUT Murata GRM188R60J106ME47D 10 µF 0603

L TDK VLCF4020T-2R2N1R7 2.2 µH 4 x 4 x 2 mm

R1 560 kΩ (VO = 3.3 V)

(2)

0402

R2 100 kΩ 0402

1. Above listed components refer to typical application. Operation of the STBB1 is not limited to the choice of these external
components.

2. R1 and R2 are calculated according to the following formula:

R1 = R2 x (VOUT/VFB - 1)
Suggested value for R2 is 100 kΩ. In order to reduce the quiescent current a maximum value of 500 kΩ is possible.

6/21 Doc ID 15474 Rev 5

STBB1XX Electrical characteristics

5 Electrical characteristics

VIN = V
otherwise specified; typical values are referred to T

Table 6. Electrical characteristics

= VEN = 3.6 V, CIN = 10 µF, C

INA

= 10 µF, L = 2.2 µH, TJ = - 40 to 85°C (unless

OUT

= 25 °C).

A

Symbol Parameter Test conditions Min. Typ. Max. Unit

V

IN

Input voltage range 2.0 5.5 V

VINA rising 1.70 1.80

V

UVLO

Under voltage lockout threshold

VINA falling 1.50 1.60

485 500 515 mV

V

FB

V

OUT

Z

FB

I

Q

I

Q

I

QSHDN

Feedback voltage

TJ = 25°C 490 500 510 mV

Output voltage range 1.2 5.5 V

FB input impedance 10 MΩ

No switching quiescent current
(VIN+VINA) (see Figure 3, 4)

Operating quiescent current
(VIN+VINA)

FB = 0.7 V, V

FB = 0.7 V, V

I

= 0 A, V

OUT

= 0 V

V

MODE

= 0 A, V

I

OUT

V

= V

MODE

Shutdown quiescent current VEN = 0 V, V

IN

= 0 V 160 250

MODE

= V

MODE

OUT

OUT

= 3.6 V 0.1 1 µA

IN

IN

= 3.3 V,

= 3.3 V,

600 750

200 µA

3.4 5.0 mA

Oscillator frequency 1300 1500 1750

freq

Frequency range for
synchronization

1300 2000

Enable input logic low VIN = 2.2 V to 5.5 V 0.4

V

EN

I

EN

Enable input logic high V

Enable pin current VEN = 5.5 V 0.01 1 µA

= 2.2 V to 5.5 V 1.2

IN

MODE/SYNC input logic low VIN = 2.2 V to 5.5 V 0.4

V

MODE/SYNC

I

MODE/SYNC

%V

OUT

%V

OUT

I

SWL

I

LKN

I

LKP

R

-N NMOS switch on resistance 0.13 0.35 Ω

DSon

-P PMOS switch on resistance 0.13 0.35 Ω

R

DSon

MODE/SYNC input logic high V

MODE/SYNC pin current V

Line regulation 2.2 V < V

Load regulation 10 mA < I

Switch current limitation VIN = 3.3 V 1.6 2.3 2.6 A

NMOS leakage current VIN = 5.5 V 0.01 1 µA

PMOS leakage current 0.01 1 µA

= 2.2 V to 5.5 V 1.2

IN

MODE/SYNC

= 5.5 V 0.01 1 µA

< 5.5 V; I

IN

< 1000 mA 1 %

OUT

= 1 mA 0.5 %

OUT

V

µA

kHz

V

V

Doc ID 15474 Rev 5 7/21