MAX6876 查看數據表（PDF） - Maxim Integrated

零件编号

产品描述 (功能)

生产厂家

MAX6876

EEPROM-Programmable, Quad, Power-Supply Tracker/Sequencer Circuit

Maxim Integrated 

EEPROM-Programmable, Quad,

Power-Supply Tracker/Sequencer Circuit

Table 1. Master/Slave Settings

REGISTER

ADDRESS

09h

EEPROM MEMORY

ADDRESS

29h

BIT RANGE

DESCRIPTION

[7:6]

If “00,” the device configuration is a single device.

If “01,” the device configuration is multiple devices, slave.

If “10,” the device configuration is multiple devices, slave.

If “11,” the device configuration is multiple devices, master.

Modes of Operation

The MAX6876 provides three different modes of opera-

tion: tracking, sequencing, and mixed modes. The

mixed mode is a combination of both tracking and

sequencing modes (see the Mixed Mode (Tracking/

Sequencing) section).

Tracking

When all selected inputs exceed their selected thresh-

olds, VTRKEN > 1.285V, and ENABLE is logic high, the

tracking process is initialized. The MAX6876 generates

an internal ramp voltage that drives the control loops

for the desired tracked voltage. The tracking functional-

ity is monitored with a comparator control block (see

the Functional Diagram and Figure 5). The comparators

monitor and control each output voltage with respect to

the common tracking ramp voltage to stay within a

±125mV differential window, monitor each tracked out-

put voltage with respect to its input voltage, and moni-

tor each output voltage with respect to GND during

power-up/retry cycles. Under normal conditions each

OUT_ voltage will track the ramp voltage until the OUT_

voltage approximates the IN_ voltage (the external

n-channel FET is saturated). The slew rate for the ramp

voltage is selected through EEPROM.

Master/Slave Operation (Tracking Only)

To support voltage tracking for more than four supplies,

combine multiple MAX6876 devices. Two MAX6876

devices (one master/one slave) track up to eight supply

voltages and four MAX6876 devices (one master and

three slaves) track up to 16 supply voltages. Each

device must be programmed to act in master or slave

mode (only one master is allowed); the default state is

single device (see Table 1). The MAX6876 outputs the

ramp control voltage with the SYNCH output when con-

figured as a master device. This ramp allows multiple

devices to synchronize with the master when slave

SYNCHs are configured as inputs. For proper function-

ality control, connect all ENABLE pins together. In mas-

ter/slave mode, all controlled supplies are tracked

up/down (no mixed sequencing/tracking modes are

supported). In master-slave application, the part is

RAMP 1 RAMP 2 RAMP 3 RAMP 4

OUT1

BIT 0

BIT 4

BIT 0

BIT 4

OUT2

BIT 1

BIT 5

BIT 1

BIT 5

OUT3

BIT 2

BIT 6

BIT 2

BIT 6

OUT4

BIT 3

BIT 7

BIT 3

BIT 7

(MSB)

(MSB)

R0Bh[7:0]

R0Ch[7:0]

Figure 6. Mapping Tracking and Sequencing Modes

intended to provide only tracking for the four supplies

(only one ramp is generated). To control one particular

channel, insert a “1” in any of the four possible posi-

tions (one row for each channel contains 4 bits) and the

circuit will generate the proper signals (see Figure 6).

For multiple MAX6876 operations, the ramp control volt-

age is brought out of the master’s SYNCH (programmed

as an output) and into the slave’s SYNCH (programmed

as an input). The highest tracked supply must be con-

nected to one of the master’s IN_ inputs. When all IN_

threshold conditions are met (on master and slaves), the

master ramp begins rising at the selected ramp slew rate.

During normal operation all OUT_ voltages (for master

and slave) track the ramp voltage. If the slave’s OUT_

voltages do not properly follow the ramp voltage (exceed

125mV differential), the slave device asserts HOLD low.

The master recognizes the HOLD and holds the ramp

voltage, allowing the slave’s slower OUT_ voltages to

______________________________________________________________________________________ 15

Share Link: