Boost Output Voltage Control

User can control the boost output voltage by boost output 8-bit register.

Boost[7:0]

Register 0Dh

BOOST Output

Voltage

(typical)

Binary

Hex

0000 0000

00

4.10

0000 0001

01

4.25

0000 0011

03

4.40

0000 0111

07

4.55 Default

0000 1111

0F

4.70

0001 1111

1F

4.85

0011 1111

3F

5.00

0111 1111

7F

5.15

1111 1111

FF

5.30

Boost Output Voltage Control

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Magnetic Boost DC/DC Converter Electrical Characteristics

Symbol

Parameter

Conditions

Min

Typ

Max

Units

I

LOAD

Load Current

3.0V

≤ V

IN

≤ 4.5V

V

0

250

mA

V

OUT

Output Voltage Accuracy (FB Pin)

1 mA

≤ I

LOAD

≤ 225 mA

3.0V

≤ V

IN

≤ V (FB)−0.5V

V

−5

+5

%

Output Voltage (FB Pin)

1 mA

≤ I

LOAD

≤ 250 mA

V

(SCHOTTKY)

4.55

V

1mA

≤ I

LOAD

≤ 250 mA

V

V

V

RDS

ON

Switch ON Resistance

V

0.4

0.5

Ω

f

PWF

PWM Mode Switching Frequency

RT = 82 k

Ω

1

MHz

Frequency Accuracy

RT = 82 k

Ω

−6

%

−10

+10

t

STARTUP

Startup Time

25

ms

I

CL_OUT

OUT Pin Current Limit

V

600

750

1050

mA

400

1200

PFM/PWM Mode

User can change the Boost converters mode between PWM (Pulse Width Modulation) and PFM (Pulse Frequency Modulation).

The startup is done on PFM mode and then the device runs on PWM mode (as a default). User can set PFM mode by turning

“pfm_mode” register bit HIGH. PFM is recommended to use with light loads and PWM with high loads.

Boost Standby Mode

User can set boost converter to STANDBY mode by writing register bit EN_BOOST low. This mode can be useful when driving

LEDs directly from battery voltage. This may be possible if LED forward voltage is low, battery voltage is high and LED current

is low.

When EN_BOOST is written high, the converter starts for 10 ms in PFM mode and then goes to PWM mode if PWM mode has

been selected (default).

Unused Boost Converter

If the boost converter is not used, it should be disabled by writing bit en_boost low. OUT pin should be connected to GND and

FB pin to the LED supply voltage.

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