Rainbow Electronics MAX16071 - Manual (Page 13)

12-Channel/8-Channel, Flash-Configurable System
Managers with Nonvolatile Fault Registers
MAX16070/MAX16071
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Boot-Up Delay
Once EN is above its threshold and the software-enable
bit is set, a boot-up delay occurs before monitoring
begins. This delay is configured in register 77h[3:0] as
shown in Tables 2 and 3.
Internal Current-Sense Amplifier
The current-sense inputs, CSP/CSM, and a current-
sense amplifier facilitate power monitoring (see Figure
4). The voltage on CSP relative to GND is also monitored
by the ADC when the current-sense amplifier is enabled
with r47h[0]. The conversion results are located in regis-
ters r19h and r1Ah (see Table 6). There are two select-
able voltage ranges for CSP set by r47h[1], see Table
4. Although the voltage can be monitored over SMBus
or JTAG, this voltage has no threshold comparators and
cannot trigger any faults. Regarding the current-sense
amplifier, there are four selectable ranges and the ADC
output for a current-sense conversion is:
X
ADC
= (V
SENSE
x A
V
)/1.4V x (2 8 - 1)
where X ADC is the 8-bit decimal ADC result in register
r18h, V SENSE is V CSP - V CSM, and A V is the current-
sense voltage gain set by r47h[3:2].
In addition, there are two programmable current-sense
trip thresholds: primary overcurrent and secondary over-
current. For fast fault detection, the primary overcurrent
threshold is implemented with an analog comparator
connected to the internal OVERC signal. The OVERC
signal can be output on one of the GPIO_s. See the
General-Purpose Inputs/Outputs section for configur-
ing the GPIO_ to output the OVERC signal. The primary
threshold is set by:
I TH = V CSTH /R SENSE
where I
TH
is the current threshold to be set, V
CSTH
is
the threshold set by r47h[3:2], and R SENSE is the value
of the sense resistor. See Table 4 for a description of
r47h. OVERC depends only on the primary overcurrent
threshold. The secondary overcurrent threshold is imple-
mented through ADC conversions and digital compari-
son set by r6Ch. The secondary overcurrent threshold
includes programmable time delay options located in
r73h[6:5]. Primary and secondary current-sense faults
are enabled/disabled through r47h[0].
Table 2. Boot-Up Delay Register
Table 3. Boot-Up Delay Values
REGISTER
ADDRESS
FLASH
ADDRESS
BIT RANGE DESCRIPTION
77h 277h
[3:0] Boot-up delay
[7:0] Reserved
CODE VALUE
0000 25Fs
0001 500Fs
0010 1ms
0011 2ms
0100 3ms
0101 4ms
0110 6ms
0111 8ms
1000 10ms
1001 12ms
1010 25ms
1011 100ms
1100 200ms
1101 400ms
1110 800ms
1111 1.6s