DS5028E Datasheet, PDF (21/41 Pages) Richtek Technology Corporation – Integrated PMIC with 4-Channel Synchronous Buck Converters, 8 LDOs, and MTP Non-Volatile Memory for Industrial Applications

RT5028E
EEPROM (MTP) Control Flow
The RT5028E embeds 32 bytes MTP memory, and it allows
users to save some I²C register bank data to MTP. When
the I²C register 0x3A Bit[0]/Bit[1] is wrote to “1”, the
MTP Page1/Page2 will execute erase process firstly.
Because the erase process will be done in every writing
time, the MTP data will be missed. So it would be best
for users to read data from MTP to I²C first before
executing writing process.
Page 1 writing follow :
Set I²C Register 0x3A Bit[4] =1
PMU will read MTP data to
relative I²C register bank.
Reading MTP process
Set I²C Register 0x3A Bit[0]
PMU will erase the MTP page1
data
Writing MTP process
PMU will move relative I²C
register bank data to MTP
Page 2 writing follow :
Set I²C Register 0x3A Bit[5] =1
PMU will read MTP data to
relative I²C register bank.
Reading MTP process
Set I²C Register 0x3A Bit[1]
PMU will erase the MTP page2
data
Writing MTP process
PMU will move relative I²C
register bank data to MTP
Copyright ©2016 Richtek Technology Corporation. All rights reserved.
DS5028E-00 October 2016
Thermal Considerations
The junction temperature should never exceed the
absolute maximum junction temperature T_J(MAX), listed
under Absolute Maximum Ratings, to avoid permanent
damage to the device. The maximum allowable power
dissipation depends on the thermal resistance of the IC
package, the PCB layout, the rate of surrounding airflow,
and the difference between the junction and ambient
temperatures. The maximum power dissipation can be
calculated using the following formula :
P_D(MAX) = (T_J(MAX) − T_A) / θ_JA
where T_J(MAX) is the maximum junction temperature, T_A is
the ambient temperature, and θ_JA is the junction-to-ambient
thermal resistance.
For continuous operation, the maximum operating junction
temperature indicated under Recommended Operating
Conditions is 125°C. The junction-to-ambient thermal
resistance, θ_JA, is highly package dependent. For a
WQFN-56L 7x7 package, the thermal resistance, θ_JA, is
27°C/W on a standard JEDEC 51-7 high effective-thermal-
conductivity four-layer test board. The maximum power
dissipation at T_A = 25°C can be calculated as below :
P_D(MAX) = (125°C − 25°C) / (27°C/W) = 3.7W for a
WQFN-56L 7x7 package.
The maximum power dissipation depends on the operating
ambient temperature for the fixed T_J(MAX) and the thermal
resistance, θ_JA. The derating curves in Figure 1 allows
the designer to see the effect of rising ambient temperature
on the maximum power dissipation.
4.0
Four-Layer PCB
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 1. Derating Curve of Maximum Power Dissipation
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