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Table 41. circular buffer read addresses, Table 42. circular buffer control register format – Rainbow Electronics MAX5961 User Manual

Page 34

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MAX5961

0 to 16V, Quad, Hot-Swap Controller
with 10-Bit Current and Voltage Monitor

34

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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