LP8754

SNVS861A – FEBRUARY 2014 – REVISED AUGUST 2014

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6-Phase Buck Electrical Characteristics (continued)

Limits apply over the full ambient temperature range -40°C

≤ TA ≤ 85°C, VVDDA5V = VVINBXX = 3.7 V, VVIOSYS = VNRST = 1.8 V,

VOUT = 1.1 V, (unless otherwise noted).

SYMBOL

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

ILIMITP

High side switch current limit 2.5 A register setting

2050

2600

3300

mA

ILIMITN

Low side switch current limit

Reverse current

650

900

1050

VOUT

Output voltage

Range, Programmable by register setting

0.6

1.0

1.67

V

Step

10

mV

fSW

Switching frequency

2.5 V

≤ VVINBXX ≤ 5 V

2.7

3.0

3.4

MHz

Test Current = 200 mA; Split FET

120

RDSON_P

Pin-pin resistance for PFET

Test Current = 200 mA; Full FET

60

m

Ω

RDSON_N

Pin-pin resistance for NFET

IOUT = –200 mA

50

ILK_HS

High-side leakage current

VSW = 0 V, Per Buck Core

2

µA

ILK_LS

Low-side leakage current

VSW = 3.7 V = VVINBXX, Per Buck Core

2

Enabled via control register, Active only

RPD

Pull-down resistor

250

Ω

when converter disabled, Per Buck Core

Differential feedback Input

RIN_FB

TA = 25°C

200

300

400

k

Ω

resistance (3)

(3)

Datasheet min/max specification limits are specified by design.

6.7 6-Phase Buck System Characteristics

Limits apply over the full ambient temperature range -40°C

≤ TA ≤ 85°C, VVDDA5V = VVINBXX = 3.7 V, VVIOSYS = VNRST = 1.8 V,

VOUT = 1.1 V, (unless otherwise noted).

SYMBOL

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Programmable via control register (1)

RAMP_B0[2:0] = 000

30

RAMP_B0[2:0] = 001

15

RAMP_B0[2:0] = 010

7.5

KRAMP

Ramp timer

RAMP_B0[2:0] = 011

3.8

mV/µs

RAMP_B0[2:0] = 100

1.9

RAMP_B0[2:0] = 101

0.94

RAMP_B0[2:0] = 110

0.47

RAMP_B0[2:0] = 111

0.23

TSTART

Start-up time

Time from NRST-HIGH to start of switching

25

µs

TRAMP

VOUT rise time

Time to ramp from 5% to 95% of VOUT

20

µs

Average output current, programmable via control

register, VOUT = 1.1 V

(2)

PFM_EXIT_B0[2:0] = 011

175

PFM-to-PWM switch–over current PFM_EXIT_B0[2:0] = 100

225

IPFM–PWM

mA

threshold

PFM_EXIT_B0[2:0] = 101

275

PFM_EXIT_B0[2:0] = 110

325

PFM_EXIT_B0[2:0] = 111

375

(1)

In the real application, achievable output voltage ramp profiles are influenced by a number of factors, including the amount of output

capacitance, the load current level, the load characteristic (either resistive or constant-current), and the voltage ramp amplitude. Typical

values are measured with typical conditions.

(2)

The final PFM-to-PWM and PWM-to-PFM switchover current varies slightly and is dependant on the output voltage, input voltage, and

the inductor current level. Typical values are measured with typical conditions.

8

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