ZM7300G Series Digital Power Manager
Data Sheet
The HRES_N function is intended as an emergency reset and except as indicated below, should
not be used in normal system operation.
It is necessary to use an external reset circuit (see Fig. 3) to hold the HRES_N line low until the VDD
supply reaches steady state conditions. Power-One Inc. successfully tested the On-Semi voltage
detector p/n NCP303LSN27T1 although other similar devices can also be utilized. Alternatively, the
HW_RES pin can be connected to the output of a CPLD (or similar device) and controlled via the
system supervisory circuitry.
10.7
Communication Interfaces
10.7.1 I2C Interface
The ZM7300 series DPMs have the industry standard I2C interface fully meeting the requirements of the
I2C -Bus Specification Version 2.1 from Philips Semiconductors. The I2C interface is working in the
following configurations:
standard (100kbs) and fast (400kbs) data transfer rates
7-bit addressing: 4 MSBs fixed, 3 LSBs programmable by ADDR[2:0]. The address prefix of the
ZM7300 is 0x50. This allows encoding DPM addresses 0x50, 0x52, …, 0x5E (Bit0 is the
read/write bit)
The DPM always acts as the I2C slave while the host processor always acts as the I2C master. Refer to
the “DPM Programming Manual” for the detailed description of the I2C communications.
Note: It is recommended to use Power-One’s ZM00056-KIT USB to I2C Adapter kit for the
communication between a DPM and a computer with the Z-One Graphical User Interface
10.7.1.1 Watchdog Timer
In order to prevent occasional hanging of the I2C bus, a watchdog timer is started whenever an I2C
command is initiated. If the command is not executed before the watchdog times out, the DPM will
assume that the I2C bus is in an error condition (e.g. the SCL or SDA lines are pulled low continuously)
and it will reset the I2C bus. The watchdog timeout is 1000ms. Since the watchdog function is not a
part of the standard I2C specifications, it can be disabled by the user.
10.7.2 JTAG Interface
The ZM7300 series DPMs feature the JTAG interface that can be used for programming the DPM with
user-specific configuration settings. JTAG boundary-scan capabilities are not currently supported.
JTAG-programmable DPMs have unique 5-digit identifiers listed in Table 6.
Table 6. JTAG Programmable DPM Part Numbers
Base Part Number
ZM7304G
5- digit identifier
65505
ZM7308G
65506
ZM7316G
65507
ZM7332G
65508
ZD-00896 Rev. 5.1, 13-Jul-10
www.power-one.com
Page 27 of 33
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