Maxim Integrated MAX6876 User Manual
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Keywords: sequencer, sequencing, monitor, eeprom, tracking,
USER GUIDE 3917
The MAX6876 Power -Supply Tracker/Sequencer User
Guide
By: Eric Schlaepfer, Applications Engineer
Sep 20, 2006
Abstract: This application note provides a step -by-step tutorial for configuring the MAX6876. The tutorial
describes how to set thresholds, timing delays, current measurements, and sequencing/tracking order.
Overview of the MAX6876's Key Features
Tracks and sequences up to four voltages
Closed- loop tracking control with programmable slew rate
Mixed tracking and sequencing
I²C programmable
Overcurrent sensing
Separate power-good (PG) outputs
Introduction
The MAX6876 tracks and sequences up to four voltages using parameters programmed over I²C and stored in
the internal EEPROM; these parameters include voltage thresholds, slew rates, timing delays, and the
sequencing order. The parameters are set within the user-friendly MAX6876 Evaluation Kit software. The part
may be programmed in-circuit using four wires: V
experimentation during prototyping very easy since no resistors or capacitors need to be replaced to change the
thresholds or timing delays. In this circuit, power during normal operation comes from IN1 (the highest of the
input voltages), and power during programming comes from V
power supplies on the board to remain off during programming.
Several passive components are required for operation. The ABP connection needs to be connected to a 1µF
ceramic capacitor to filter the internal power supply. All of the status outputs are open drain and, accordingly,
require pullup resistors. These resistors can be connected to any power-supply voltage under +6V. To filter
noise on the IN_ connections, 0.1µF capacitors can be connected, but they are not absolutely necessary.
Figure 1 illustrates the basic connections and key features of the MAX6876.
, SDA, SCL, and GND. In - circuit programming makes
CC
. This configuration allows the main DC -DC
CC
Figure 1. A diagram of the MAX6876's basic connections.
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To create a basic design with the MAX6876, use the following steps:
1. Download and install the MAX6876 Evaluation Kit software.
2. Connect a CMOD232 board (included in the Evaluation Kit) to the host computer using an RS232 cable
(not a "null modem" type cable). Note that the MAX6876 Evaluation Kit software does not yet support the
newer CMAXQUSB interface board.
3. Connect the CMOD232 board to either the MAX6876 Evaluation Kit or the application circuit board. The
pinout of the CMOD232 connector P3 is as follows:
Figure 2. The pinout of the CMOD232 connector P3.
4. To connect to the CMOD232 and the MAX6876, launch the Evaluation Kit software, select System-