ETA1188

www.etasolution.com

11

Powering Minds of the Smart

VOUT CONDITION

Q1 BEHAVIOUT

BOOST CC

REGULATION

ISET REGULATION

VOLATGE

VOUT< VIN

VOUT< 2.5V

NO

NO

Full Open

Activated

1.0V

YES

NO

Current Regulation

Inactivated

0.8V

ANY

YES

Current Regulation

Inactivated

0.5V

Output current level IBSTOUT is set by ISET pin resistor. Current is sensed to ISET pin is 1/5000 of Q1 current, then

IBSTOUT is given by following equation:

I

5000

( )

ISET

BSTOUT

ISET

V

A

R

=

×

BOOST OUTPUT OVER VOLTAGE PROTECTION

At some conditions that PMID could hit PMID_OVP threshold, boost will stop switching immediately and operate again

when PMID goes back to normal. In this condition, Q1 is still fully turned on.

Besides PMID over voltage protection, ETA1188 integrates FB over voltage protection that when FB voltage hits

VFB_OVP, boost will stop switching immediately and operate again when FB goes back to normal. This feature to

protect output connected device when VIN is higher than regulation level.

BOOST HICCUP OPERATION

During operation if one of FB_UVP or VOUT_OCP occurs, ETA1188 starts HICCUP mode that both Q1 and boost are

disabled in 12ms then retried in 4ms. It will exit HICCUP mode when fault conditions are removed in 4ms retrying.

THERMAL SHUTDOWN

ETA1188 is shutdown when junction temperature gets higher than 155˚C. And it will be back to normal operation when

cooler than 120˚C.

APPLICATION INFORMATION

VOUT OUTPUT VOLTAGE CONFIGURATION

FB pin voltage is regulated to 1.2V, so feedback resistors are given by following equation:

1

2

OUT

2

RR

V

1.2

(V)

R

+

=

×

For example, if R2 = 55kΩ, R1 is given by below table:

VOUT(V)

R1 (kΩ)

VOUT(V)

R1 (kΩ)

5.06

180

9.13

370

5.91

220

10.41

430

6.99

270

11.27

470

8.27

330

12.13

510