MAX77816 datasheet(8/26 Pages) MAXIM

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Detailed Description

Enable Control

When EN pin is set to high, the IC turns on the

internal bias circuitry which takes typically 100µs

(tON_DLY) to be settled. As soon as the bias is ready, all

user registers are accessible through I2C. Write BB_EN

bit to 1 to enable (register default) buck-boost output

voltage regulation. The VOUTBB takes 800µs (tSS) to the

nominal regulated voltage after BB_EN’s setting.

When EN pin is pulled low, the IC goes into shut-

down mode. This event also resets all type-O

registers to their POR default values.

Immediate Turn-Off Events

The following events initiate immediate turn-off.

● Thermal protection (TJ > +165°C)

● VSYS < SYS UVLO falling threshold (VUVLO_F)

● Overcurrent protection

(ILIM is consistently hit for 3ms)

The events in this category disable buck-boost until the

hazardous condition come back to normal conditions.

Inductor Peak Current Limit (ILIM)

The buck-boost regulator’s high-side MOSFETs peak

current limit (ILIM_LXBB) is register programmable.

Applications can use ILIM_LXBB programmability to

ensure that the regulator never exceeds the saturation

current rating of the inductor on the PCB. In MAX77816B,

ILIM_LXBB is GPIO pin programmable. Refer to the

Multifunction GPIO Pin section.

Multifunction GPIO Pin

The IC has a general-purpose input and output (GPIO)

pin which can be configured as 5 different functions

through GPIO_CFG[2:0]. The default function of the GPIO

pin is listed below:

●

MAX77816A: FPWM Mode Enable

When the GPIO pin is connected to GND, the buck-

boost regulator automatically transitions from SKIP

mode to fixed frequency operation (PWM) as load

current increases. SKIP mode helps maximize the

buck-boost regulator’s efficiency at light load. When

the GPIO is connected to a voltage above VGPI_H,

forced PWM (FPWM) switching behavior is enabled.

The FPWM mode benefits applications where lowest

output ripple is required. The BB_FPWM bitfield is

ignored when GPIO_CFG[2:0] = 001b.

●

MAX77816B: Inductor Peak Current-Limit (ILIM)

Selection

The buck-boost regulator’s high-side MOSFETs peak

current limit (ILIM_LXBB) is GPIO pin programmable.

The ILIM[1:0] bitfield is ignored when GPIO_CFG[2:0]

= 010b. Connect GPIO to GND to set ILIM to 1.8A

(typ). Connect GPIO to a voltage above VGPI_H to

program ILIM to 5A (typ).

●

MAX77816C: Output Voltage Selection

The GPIO pin sets the output voltage dynamically

between VOUT[6:0] (GPIO = LOW) and VOUT_H[6:0]

(GPIO = HIGH). When EN pin is asserted, the status

of the GPIO pin is latched until completing soft-start

so that changes on the GPIO pin are ignored. After

soft-start is done, internal logic sets VOUTBB based

on the GPIO input.

●

MAX77816D: Power-OK (POK) Indicator

The device features an open-drain GPIO out-

put to monitor the output voltage. The GPIO pin

requires an external pullup resistor. GPIO goes high

(high-impedance) after the output increases above

92.5% (VPOK_R) of the nominal regulated voltage

(VOUT_REG). GPIO goes low when the regulator

output drops below 90% (VPOK_F) of VOUT_REG.

●

MAX77816E: Interrupts Indicator

The GPIO indicates the application processor that the

status of the device has changed.

INT[3:0], INT_MASK[3:0], and the GPIO pin work

together to present the buck-boost regulator’s abnor-

mal status, including overvoltage, overcurrent, power

OK, and thermal shutdown. GPIO goes low when one

or more bits of INT[3:0] becomes 1, and the related

interrupts are not masked in INT_MASK[3:0]. GPIO

becomes high (cleared) as soon as the read action of

INT[3:0] starts.

Table 1. Enable Control Logic Truth Table

EN PIN

BB_EN BIT

OPERATING MODE

low

Device off

high

Disable output

high

1 (default)

Enable output

MAX77816

High-Efficiency Buck-Boost Regulator

with 5A Switches

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