MIC7400_15 Datasheet, PDF (62/68 Pages) Micrel Semiconductor – Configurable PMIC, Five-Channel Buck Regulator Plus One-Boost with HyperLight Load® and I2C Control

Micrel, Inc.
MIC7400
Soft-Start Registers (18’h − 1A’h)
When regulator(n) is turned on from either the Enable Register (04’h) in NORMAL mode or from the Standby Register
(03’h) in STANDBY mode, then the three REG(n)SS soft-start bits are used to control both the rising and falling ramp rate
of the outputs.
In NORMAL mode, the outputs are stepped from the current regulator voltage settings to a newly-programmed regulator
voltage setting or to the default value.
On power-up, the regulator voltage output is set to the lowest possible voltage setting which is 3F’h. The voltage regulator
will change by one step or increment at a time. The amount of time between each step is controlled by the soft-start
registers. Table 21 details the amount of time for each encoded soft-start value.
Table 21. Soft-Start Register Speed Settings
R/W Default Description
Soft-Start Time from 4µs to 512µs
SS_SPEED = 0 R/W
000 000 = 4µs
010 = 16µs
001 = 8µs
011 = 32µs
Soft-Start Time from 8µs to 1024µs
SS_SPEED = 1 R/W
000 000 = 8µs
010 = 32µs
001 = 16µs
011 = 64µs
100 = 64µs
101 = 128µs
100 = 128µs
101 = 256µs
110 = 256µs
111 = 512µs
110 = 512µs
111 = 1024µs
Table 22. Soft-Start Register OUT1 and OUT2
Register Name SS1-2_REG
Soft-Start Register for VOUT1 and VOUT2
Address
0x18’h
Field
bit R/W Default Description
REG1SS
2:0 R/W
001
(8µs)
OUT1 Soft-Start Time
See Table 19 for Soft-Start Settings
REG2SS
5:3 R/W
001
(8µs)
OUT2 Soft-Start Time
See Table 19 for Soft-Start Settings
6 R/W
0
Reserved
SS_SPEED
7 R/W
Set the speed of the clock to slow or fast for different clock division, see Table 19.
0
0 = Slow Speed
1 = Fast Speed
Table 23. Soft-Start Register OUT3 and OUT4
Register Name
SS3-4_REG
Soft-Start Register for VOUT3 and VOUT4
Address
0x19’h
Field
bit R/W Default Description
REG3SS
2:0 R/W
001
(8µs)
OUT3 Soft-Start Time
See Table 19 for Soft-Start Settings
REG4SS
5:3 R/W
001
(8µs)
OUT4 Soft-Start Time
See Table 19 for Soft-Start Settings
6 R/W
0
Reserved
7 R/W
0
Reserved
March 3, 2015
62
Revision 2.0