Manual

MAX5961
0 to 16V, Quad, Hot-Swap Controller
with 10-Bit Current and Voltage Monitor
34 ______________________________________________________________________________________
Circular Buffer
The MAX5961 features eight 10-bit circular buffers (in
volatile memory) that contain a history of the 50 most-
recent voltage and current digital conversion results for
each hot-swap channel. These circular buffers can be
read back through the I
2
C interface. The recording of
new data to the buffer for a given signal is stopped
under any of the following conditions:
• The corresponding channel is shut down because of
a fault condition
• A read of the circular buffer base address is per-
formed through the I
2
C interface
• The corresponding channel is turned off by a combi-
nation of the Chx_EN1, Chx_EN2, or ON_ signals
The buffers allow the user to recall the voltage and cur-
rent waveforms for analysis and troubleshooting. The
buffer contents are accessed through the I
2
C interface
at eight fixed addresses in the MAX5961 register
address space (see Table 41).
Each of the eight buffers can also be stopped under
user control by register cbuf_chx_store (see Table 42).
The contents of a buffer can be retrieved as a block
read of either 50 10-bit values (spanning 2 bytes each)
or of 50 high-order bytes, depending on the per-signal
bit settings of register cbufrd_hibyonly (see Table 43).
Table 41. Circular Buffer Read Addresses
ADDRESS NAME DESCRIPTION
0x80 cbuf_ba_ch1_v Base address for channel 1 voltage buffer block read
0x81 cbuf_ba_ch1_i Base address for channel 1 current buffer block read
0x82 cbuf_ba_ch2_v Base address for channel 2 voltage buffer block read
0x83 cbuf_ba_ch2_i Base address for channel 2 current buffer block read
0x84 cbuf_ba_ch3_v Base address for channel 3 voltage buffer block read
0x85 cbuf_ba_ch3_i Base address for channel 3 current buffer block read
0x86 cbuf_ba_ch4_v Base address for channel 4 voltage buffer block read
0x87 cbuf_ba_ch4_i Base address for channel 4 current buffer block read
Table 42. Circular Buffer Control Register Format
Description: Circular buffer run-stop control register (per-buffer control: 1 = run, 0 = stop)
Register Title: cbuf_chx_store
Register Address: 0x31
R/W R/W R/W R/W R/W R/W R/W R/W
RESET
VALUE
ch4_i_run ch4_v_run ch3_i_run ch3_v_run ch2_i_run ch2_v_run ch1_i_run ch1_v_run 0xFF
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
Table 43. Circular Buffer Resolution Register Format
Description:
Circular buffer read-out resolution: high-order byte only, or 8-2 split 10-bit data
(per-buffer control: 1 = high-order byte output, 0 = full-resolution 10-bit output)
Register Title: cbufrd_hibyonly
Register Address: 0x6D
R/W R/W R/W R/W R/W R/W R/W R/W
RESET
VALUE
ch4_i_res ch4_v_res ch3_i_res ch3_v_res ch2_i_res ch2_v_res ch1_i_res ch1_v_res 0x00
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0