High-Efficiency LCD Boost

with True Shutdown

4

_______________________________________________________________________________________

EFFICIENCY vs. BATTERY VOLTAGE

(FIGURE 4)

BATTERY VOLTAGE (V)

10

8

6

4

2

50

60

70

80

90

100

40

012

L1 = MURATA LQH32CN220K23

5mA LOAD

1mA LOAD

EFFICIENCY vs. LOAD CURRENT

WITH 22

µH INDUCTOR

LOAD CURRENT (mA)

10

1

50

60

70

80

90

100

40

0.1

100

MAX8574, TOKO A914BYW-220M

MAX8571, MURATA LQH32CN220K23

MAX8570, MURATA LQH32CN220K23

EFFICIENCY vs. LOAD CURRENT

WITH 47

µH INDUCTOR

LOAD CURRENT (mA)

10

1

50

60

70

80

90

100

40

0.1

100

MAX8570, L1 = MURATA LQH32CN470K23

MAX8571, L1 = TOKO A914BYW-470M

PEAK INDUCTOR CURRENT LIMIT

vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

5.1

4.7

4.3

3.9

3.5

3.1

100

200

300

400

500

600

700

0

2.7

5.5

MAX8574

MAX8571

MAX8570

SUPPLY CURRENT vs. LOAD CURRENT

LOAD CURRENT (mA)

10

5

20

40

60

80

100

120

0

015

L1 = MURATA LQH32CN220K23

NO-LOAD CURRENT vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

5

4

1

2

3

10

20

30

40

50

60

70

80

0

06

R1 = 3.9M

Ω

R2 = 287k

Ω

R1 = 7.87M

Ω

R2 = 576k

Ω

MAX8573,

FIGURE 3

L1 = MURATA

LQH32CN220K23

NO SWITCHING

LINE TRANSIENT 3V TO 5.5V (MAX8571)

MAX8570/71/73/74/75 toc13

100

µs/div

200mV/div

(AC-COUPLED)

2V/div

0

3.6k

Ω LOAD, R1 = 3.9MΩ, R2 = 287kΩ

LINE TRANSIENT 3V TO 5.5V

(FIGURE 3, MAX8573)

MAX8570/71/73/74/75 toc14

100

µs/div

200mV/div

(AC-COUPLED)

2V/div

0

3k

ΩLOAD

Typical Operating Characteristics (continued)

°C, unless otherwise noted.)