Rainbow Electronics MAX5970 - Manual (Page 31)

0V to 16V, Dual Hot-Swap Controller with 10-Bit
Current and Voltage Monitor and 4 LED Drivers
MAX5970
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Table 41. Circular Buffer Read Addresses
Table 42. Circular Buffer Control Register Format
Table 43. Circular Buffer Resolution Register Format
Circular Buffer
The MAX5970 features four 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.
• Clearing appropriate bits in register cbuf_chx_store.
• 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 four fixed addresses in the MAX5970 register address
space (see Table 41).
Each of the four 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 fifty 10-bit values (spanning 2 bytes each) or of fifty high-order bytes, depending on the per-signal bit
settings of register cbufrd_hibyonly (see Table 43).
ADDRESS NAME DESCRIPTION
0x46 cbuf_ba_ch0_v Base address for channel 0 voltage buffer block read
0x47 cbuf_ba_ch0_i Base address for channel 0 current buffer block read
0x48 cbuf_ba_ch1_v Base address for channel 1 voltage buffer block read
0x49 cbuf_ba_ch_i Base address for channel 1 current buffer block read
Description: Circular buffer run-stop control register (per-buffer control: 1 = run, 0 = stop)
Register Title: cbuf_chx_store
Register Address: 0x19
R R R R R/W R/W R/W R/W
RESET
VALUE
— — — — Ch1_i_run Ch1_v_run Ch0_i_run Ch0_v_run 0x0F
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
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: 0x3F
R R R R R/W R/W R/W R/W
RESET
VALUE
— — — — Ch1_i_res Ch1_v_res Ch0_i_res Ch0_v_res 0x0F
bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0