MAX6746KA46+T Maxim Integrated, MAX6746KA46+T Datasheet - Page 15

• Manufacturer Part Number: MAX6746KA46+T
• Description: Supervisory Circuits
• Manufacturer: Maxim Integrated
• Series: MAX6746, MAX6747, MAX6748, MAX6749, MAX6750, MAX6751, MAX6752, MAX6753r

Specifications of MAX6746KA46+T

• Number Of Voltages Monitored: 1
• Monitored Voltage: 1.575 V to 5 V
• Undervoltage Threshold: 4.533 V
• Overvoltage Threshold: 4.718 V
• Output Type: Active Low, Push-Pull
• Manual Reset: Resettable
• Watchdog: Watchdog
• Battery Backup Switching: No Backup
• Power-up Reset Delay (typ): 9.487 ms
• Supply Voltage - Max: 5.5 V
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Package / Case: SOT-23
• Chip Enable Signals: No
• Maximum Power Dissipation: 714 mW
• Minimum Operating Temperature: - 40 C
• Power Fail Detection: No
• Supply Current (typ): 5 uA
• Supply Voltage - Min: 1 V

During the PD classification mode, the MAX5984 forces
a probe voltage (-18V typ) at DET and measures the
current into DET. The measured current determines the
class of the PD. If the ILIM1 and ILIM2 pins are both left
unconnected, the MAX5984 classifies the PD based on
Table 33.9 of the IEEE 802.3at standard (Table 2). If the
measured current exceeds 51mA, the MAX5984 does
not power the PD, but returns to the idle state before
attempting a new detection cycle.
The MAX5984 supports high power beyond the IEEE
802.3at standard by providing an additional classifica-
tion (Class 5) if needed. To enable Class 5 detection
and select the corresponding current-limit/overcurrent
thresholds, ILIM1 and ILIM2 must be set based on
the combinations detailed in Table 3. Once Class 5 is
Table 2. PSE Classification of a PD (Table
33.9 of the IEEE 802.3at Standard)
Table 3. Class 5 Overcurrent Threshold and Current-Limit Settings
MEASURED I
CONFIGURATION
> 13 and < 16
> 21 and < 25
> 31 and < 35
> 45 and < 51
Unconnected
Unconnected
> 5 and < 8
16 to 21
25 to 31
35 to 45
Single-Port, 40W, IEEE 802.3af/802.3at PSE
8 to 13
0 to 5
ILIM1
V
V
EE
EE
CLASS
______________________________________________________________________________________
(mA)
Class 5 PD Classification
Controller with Integrated MOSFET
Either Class 4 or Invalid
Can be Class 0 or 1
CLASSIFICATION
Either Class 1 or 2
Either Class 2 or 3
Either Class 3 or 4
PD Classification
CONFIGURATION
Unconnected
Unconnected
Class 0
Class 1
Class 2
Class 3
Class 4
ILIM2
V
V
EE
EE
enabled, during classification, if the MAX5984 detects
currents in excess of the Class 4 upper limit threshold,
the PD is classified as a Class 5 PD. The PD is guar-
anteed to be classified as a Class 5 device for any
classification current from 51mA up to the classification
current-limit threshold.
The Class 5 overcurrent threshold and current limit is
set with ILIM1 and ILIM2. ILIM1 and ILIM2 are both
referenced to V
digital supply. Leave ILIM1 and ILIM2 unconnected to
disable Class 5 detection and to be fully compliant to
IEEE 802.3at standard classification. Class 5 detection
is enabled, and the corresponding overcurrent threshold
and current limit is adjusted, by connecting one or both
to V
If the result of the first classification event is Class 0
through Class 3, then only a single classification event
occurs, as shown in Figure 1. However, if the result is
Class 4 or Class 5 (when enabled), the device performs
a second classification event, as shown in Figure 2.
Between the classification cycles, the MAX5984 per-
forms a first and second mark event as required by the
IEEE 802.3at standard, forcing a -9.0V probing voltage
at DET. The 2-Event function is disabled by default in the
MAX5984A/MAX5984B/MAX5984E. However, it is not
pin-selectable in the MAX5984E.
When the MAX5984 enters a powered state, the t
and t
timed out, the device enters a normal powered condition,
allowing power delivery to the PD.
THRESHOLD (mA)
EE
OVERCURRENT
Class 5 disabled
DISC
(Table 3).
748
792
836
timers are reset. When the startup timer has
EE
and are internally pulled up to the
2-Event PD Classification
Class 5 disabled
LIMIT (mA)
CURRENT
Powered State
850
900
950
FAULT
15