FN8713 Rev 6.00

Page 1 of 23

September 22, 2016

FN8713

Rev 6.00

September 22, 2016

ISL78235

5A Automotive Synchronous Buck Regulator

DATASHEET

The ISL78235 is a highly efficient, monolithic, synchronous

step-down DC/DC converter that can deliver 5A of continuous

output current from a 2.7V to 5.5V input supply. The device uses

peak current mode control architecture to achieve very low duty

cycle operation at high frequency with fast transient response and

excellent loop stability.

The ISL78235 integrates a low ON-resistance P-channel

(35mΩ, typical) high-side FET and N-channel (11mΩ, typical)

low-side FET to maximize efficiency and minimize external

component count. The 100% duty cycle operation allows less

than 250mV dropout voltage at 5A output current. The

operating frequency of the Pulse Width Modulator (PWM) is

adjustable from 500kHz to 4MHz. The default switching

frequency of 2MHz is set by connecting the FS pin high.

The ISL78235 can be configured for discontinuous (PFM) or

forced continuous (PWM) operation at light load. Forced

continuous operation reduces noise and RF interference, while

discontinuous mode provides higher efficiency by reducing

switching losses at light loads.

Fault protection is provided by internal hiccup mode current

limiting during short-circuit and overcurrent conditions. The

device also integrates output overvoltage and

over-temperature protections. A power-good monitor indicates

when the output is in regulation. The ISL78235 offers a 1ms

Power-Good (PG) timer at power-up.

When in shutdown, the ISL78235 discharges the output

capacitor through an internal 100Ω soft-stop switch. Other

features include internal fixed or adjustable soft-start and

internal/external compensation.

The ISL78235 is available in a 3mmx3mm 16 Ld Thin Quad Flat

No-lead (TQFN) Pb-free package and in a 5mmx5mm 16 Ld

Wettable Flank Quad Flat No-Lead (WFQFN) package with an

exposed pad for improved thermal performance. The

ISL78235 is rated to operate across the temperature range of

-40°C to +105°C in the 3mmx3mm package and -40°C to

+125°C in the 5mmx5mm package.

Features

• 2.7V to 5.5V input voltage range

• 2MHz default switching frequency

• 100ns guaranteed phase minimum on time for wide output

regulation

• Adjustable switching frequency from 500kHz to 4MHz

• External synchronization from 1MHz to 4MHz

• Optional PFM mode for light-load efficiency improvement

• Very low ON-resistance HS/LS switches: 35mΩ/11mΩ

• Internal 1ms or adjustable external soft-start

• Soft-stop output discharge during disable

• OTP, OCP, output OVP, input UVLO protections

• 1% reference accuracy over-temperature

•Up to 95% efficiency

• AEC-Q100 qualified

• Common pinout family allows migration from 3A to 5A

without PCB change:

- ISL78233 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3A

- ISL78234 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4A

- ISL78235 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5A

Applications

• DC/DC POL modules

• μC/µP, FPGA and DSP power

• Video processor/SOC power

• Automotive infotainment power

Related Literature

• UG015, “ISL7823xEVAL1Z Evaluation Board User Guide”

• ISL78233, ISL78234 Datasheet

• UG062, “ISL7823xEVAL2Z Evaluation Board User Guide”

FIGURE 1. TYPICAL APPLICATION: 5A BUCK REGULATOR

1

3

4

VIN

VDD

SYNC

2

7

5

6

FB

PGND

PG

8

11

9

10

16

13

15

14

12

SGND

PGND

2.7V TO 5.5V

5A LOAD

DSP, FPGA

*ISL78235

*Pin Compatible

ISL78233 - 3A BUCK

ISL78234 - 4A BUCK

L

40

50

60

70

80

90

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

OUTPUT LOAD (A)

4.5

5.0

100