MIC23156 Datasheet, PDF (17/22 Pages) Micrel Semiconductor – 1.5A, 3MHz Synchronous Buck Regulator with HyperLight Load® and I2C Control for Dynamic Voltage Scaling

Micrel, Inc.
MIC23156
Table 3. Enable and Status Register (REG1) Bit Field Description
Bits
Name
R/W POR Description
7
Reserved
R
0
6
TSD
R
0
Thermal shutdown status bit. This register bit will be set by internal hardware if a thermal
shutdown event is triggered by the die temperature exceeding shutdown temperature.
5
UVLO
R
0
Undervoltage lockout status bit. This register bit will be set by internal hardware when the
under voltage lockout circuit is active, and cleared when VIN exceeds the UVLO threshold.
Power good status bit. This register will be set when the buck regulator output voltage is >
4
PGOOD
R
0 nominally 10% of the output voltage set points as specified by VSEL, BUCK_OUT1 and
BUCK_OUT2. This regulator has the same function as the PGOOD output pin.
3:2 Reserved R/W 00
1
SSL
R/W
0
Long soft-start enable bit. If this bit is set, then the internal soft start resistor is increased and
the soft start time will be extended.
0
BUCK_EN R/W
1
Buck regulator enable bit. Setting this bit will enable and turn on the buck regulator output.
Clearing this bit will disable the buck regulator output.
Table 4. BUCK_OUT1 (REG2) Bit Field Description
Bits
Name
R/W POR Description
Buck output voltage 1 setting for VSEL = 0. Setting this register value will change the
7:0
BUCK_OUT1
R/W
0X1E
output regulation point for the buck regulator when VSEL = 0. If the buck is enabled and
VSEL = 0, changing the value will immediately cause the output voltage to transition to
the new set point.
Table 5. BUCK_OUT2 (REG3) Bit Field Description
Bits
Name
R/W POR Description
Buck output voltage 2 setting for VSEL = 1. Setting this register value will change the
7:0
BUCK_OUT2
R/W
0X0A
output regulation point for the buck regulator when VSEL = 1. If the buck is enabled and
VSEL = 1, changing the value will immediately cause the output voltage to transition to
the new set point .
Calculating DAC Voltage Code
If the desired output voltage is 1.8V, then using Equation 6:
( ) V_OUT = 0.7 + 0.01× REG_{BUCK _ OUT}
→ REG_{BUCK _ OUT}
=
(1.8 − 0.7)
0.01
→ REG_{BUCK_OUT} = 110 in decimal, 6E in hex, or 0110 1110 in binary
April 22, 2013
17
Revision 1.0