POWER — Power supply

nPM6001 has six power rails that are controlled independently. Four of the power rails can be managed by highly efficient buck regulators. The two remaining power rails are managed by the LDO regulators.

The power supply is managed through TWI. BUCK[0..2] are partially controlled through TWI, meaning the output voltage and mode can be set using TWI, but they can not be switched on or off. BUCK3, LDO0, and LDO1 are fully controlled through TWI.

Parent topic: nPM6001 Product Specification

BUCK — Buck regulators

BUCK consists of four step-down regulators with the following features:

  • High efficiency (low IQ) and low noise operation
  • PWM and Hysteretic modes
  • MODE control pin for setting PWM mode to minimize output voltage ripple
All BUCK_MODE[n] pins can be used to control any BUCK[n]. The buck regulators can be forced to PWM mode by setting bit SETFORCEPWM in register BUCK[n]CONF.PWM.MODE. PWM mode provides smaller output voltage ripple.

Pin control is enabled by setting bit SWREADY. BUCK[n] goes into Hysteretic mode when BUCK_MODE[n] is LOW. When BUCK_MODE[n] is HIGH, PWM mode is set.

The thermal sensor can be set to automatically turn on when BUCK[n] is running in PWM mode. To save power, the sensor is automatically switched off when all buck regulators are in Hysteretic mode.

BUCK[n] continues to run when an overcurrent is detected but its performance is reduced. When the current stabilizes, BUCK[n] resumes normal operation.

BUCK0

BUCK0 is an always-on buck regulator. It is running when VIN is above the Power-on reset threshold and ENABLE is HIGH.

The default output voltage for BUCK0 is 1.8 V. BUCK0 can supply load currents up to 200 mA in PWM mode and up to 30 mA in Hysteretic mode. The output voltage can be programmed in 100 mV steps between 1.8 V and 3.3 V and includes overcurrent detection. Output voltage settings for both PWM and Hysteretic mode must be identical.

The following are registers for BUCK0 output voltage programming:
Table 1. BUCK0 output voltage
Registers Description
BUCK0.VOUT.ULP Output voltage setting in hysteretic mode
BUCK0.VOUT.PWM Output voltage setting in PWM mode
TASKS_UPDATE_VOUTPWM Task for applying a new BUCK0VOUTPWM register value.

The (decimal) code for a given output voltage VO0 can be calculated using equation Code = (VO0 - 1.8 V) / 0.1 V.

To change output voltage while BUCK0 is running, BUCK0 must be set first to PWM mode before writing a new setting. This ensures a smooth voltage ramp. Hysteretic mode can be used again after a trigger task.

Electrical specification

Table 2. BUCK0 electrical specification
Symbol Description Min. Typ. Max. Units
VINBUCK0 Regulator input voltage 3.0   5.5 V
VO0 Regulator output voltage range 1.8   3.3 V
VO0STEP Output voltage programming step   100   mV
VACCPWM

Output voltage accuracy

Average voltage, not including ripple or transients

PWM mode

 -5   5 %
VACCH

Output voltage accuracy

Average voltage, not including ripple or transients

Hysteretic mode

 -5   5 %
VDO0 Drop out voltage (IOUT = 100 mA)   350   mV
VO0RIPPLE_H Output voltage peak-to-peak ripple in Hysteretic mode   50   mV
VO0RIPPLE_PWM Output voltage peak-to-peak ripple in PWM mode over output current range     10 mV
IOUT_PWM Output current range, PWM mode 0   200 mA
IOUT_H Output current range, Hysteretic mode 0   30 mA
LOADTR

Load transient regulation, IOUT rises or falls between 10 mA - 150 mA in 10 μs

PWM mode

 -50   50 mV
LINETR

Line transient regulation, VINBUCK0 voltage rises or falls 300 mV in 10 μs with 1 kHz rate

PWM mode

   +/- 10   mV
EFF100MA

BUCK efficiency with 100 mA load current

VINBUCK0 = 3.8 V, VO0 = 1.8 V, T = 25°C

PWM mode

   90   %

Electrical characteristics

Figure 1. BUCK0 efficiency vs. load current (VINBUCK0 = 3.8 V, VO0 = 1.8 V)
BUCK0 efficiency vs. load current
Figure 2. BUCK0 efficiency vs. load current (VINBUCK0 = 3.8 V, VO0 = 3.3 V)
BUCK0 efficiency vs. load current
Figure 3. BUCK0 load transient (VINBUCK0 = 3.8 V, VO0 = 1.8 V, ILOAD 10 mA - 150 mA)
BUCK0 load transient
Figure 4. VO0 vs. temperature (VINBUCK0 = 3.8 V, VO0 = 1.8 V)
VO0 vs. temperature
Figure 5. VO0 vs. temperature (VINBUCK0 = 3.8 V, VO0 = 3.3 V)
VO0 vs. temperature
Figure 6. Mode transition from hysteretic to PWM (VINBUCK0 = 3.8 V, VO0 = 1.8 V, I_OUT = 10 mA)
Mode transition from hysteretic to PWM

BUCK1

BUCK1 is an always-on buck regulator. It is running when VIN is above the Power-on reset threshold, ENABLE is HIGH, and the external components are present.

The default output voltage for BUCK1 is 0.8 V. BUCK1 can supply load currents up to 150 mA in PWM mode and up to 30 mA in Hysteretic mode. The output voltage can be programmed in 50 mV steps and must be between 0.7 V and 1.4 V. Output voltage settings for both PWM and Hysteretic mode must be identical.

The following registers are for BUCK1 output voltage programming:
Table 3. BUCK1 output voltage
Register Description
BUCK1.VOUT.ULP Output voltage setting in hysteretic mode
BUCK1.VOUT.PWM Output voltage setting in PWM mode
TASKS_UPDATE_VOUTPWM Task for applying a new BUCK1VOUTPWM register value.

The (decimal) code for a given output voltage VO1 can be calculated using equation Code = (VO1 - 0.7 V) / 0.05 V.

To change output voltage while BUCK1 is running, BUCK1 must be set first to PWM mode before writing a new setting. This ensures a smooth voltage ramp. Hysteretic mode can be used again after a trigger task.

Electrical specification

Table 4. BUCK1 electrical specification
Symbol Description Min. Typ. Max. Units
VINBUCK1 Regulator input voltage 3.0   5.5 V
VO1 Regulator output voltage range 0.7   1.4 V
VO1STEP Output voltage programming step   50   mV
VACCPWM

Output voltage accuracy

Average voltage, not including ripple or transients

PWM mode

 -5   5 %
VACCH

Output voltage accuracy

Average voltage, not including ripple or transients

Hysteretic mode

 -5   -5 %
IOUT_PWM Output current range, PWM mode 0   150 mA
IOUT_H Output current range, Hysteretic mode 0   30 mA
VORIPPLE_H Output voltage peak-to-peak ripple in Hysteretic mode   50   mV
VORIPPLE_PWM Output voltage peak-to-peak ripple in PWM mode     10 mV
LOADTR

Load transient regulation

IOUT rises or falls between 10 mA - 150 mA in 10 μs

PWM mode

 -50   50 mV
LINETR

Line transient regulation

VINBUCK1 voltage rises or falls 300 mV in 10 μs with 1 kHz rate

PWM mode

   +/- 10   mV
EFF100MA

BUCK efficiency with 100 mA load current

VINBUCK1 = 3.8 V, VO1 = 0.8 V, T = 25°C

PWM mode

   84   %

Electrical characteristics

Figure 7. BUCK1 efficiency vs. load current (VINBUCK1 = 3.8 V, VO1 = 0.8 V)
BUCK1 efficiency vs. load current
Figure 8. BUCK1 load transient (VINBUCK1 = 3.8 V, VO1 = 0.8 V, ILOAD 10 mA - 150 mA)
BUCK1 load transient
Figure 9. VO1 vs. temperature (VINBUCK1 = 3.8 V, VO1 = 0.8 V)
VO1 vs. temperature
Figure 10. Mode transition from hysteretic to PWM (VINBUCK1 = 3.8 V, VO1 = 0.8 V, I_OUT = 10 mA)
Mode transition from hysteretic to PWM

BUCK2

BUCK2 is an always-on buck regulator. It is running when VIN is above the Power-on reset threshold, ENABLE is HIGH, and the external components are present.

The default output voltage for BUCK2 is 1.2 V. The regulator can supply load currents up to 150 mA in PWM mode and up to 30 mA in Hysteretic mode. The output voltage can be programmed in 50 mV steps between 1.2 V and 1.4 V. Output voltage settings for both PWM and Hysteretic mode must be identical.

The following registers are for BUCK2 output voltage programming:

Table 5. BUCK2 output voltage registers
Register Description
BUCK2.VOUT.ULP Output voltage setting in hysteretic mode
BUCK2.VOUT.PWM Output voltage setting in PWM mode
TASKS_UPDATE_VOUTPWM Task for applying a new BUCK2VOUTPWM register value.

The (decimal) code for a given output voltage VO2 can be calculated using equation Code = 10 + (VO2 - 1.2 V) / 0.05 V.

To change output voltage while BUCK2 is running, BUCK2 must be set first to PWM mode before writing a new setting. This ensures a smooth voltage ramp. Hysteretic mode can be used again after a trigger task.

Electrical specification

Table 6. BUCK2 electrical specification
Symbol Description Min. Typ. Max. Units
VINBUCK2 Regulator input voltage 3.0   5.5 V
VO2 Regulator output voltage range 1.2   1.4 V
VO2STEP Output voltage programming step   50   mV
VACCPWM

Output voltage accuracy

Average voltage, not including ripple or transients

PWM mode

 -5   5 %
VACCH

Output voltage accuracy

Average voltage, not including ripple or transients

Hysteretic mode

 -5   -5 %
IOUT_PWM Output current range, PWM mode 0   150 mA
IOUT_H Output current range, Hysteretic mode 0   30 mA
VORIPPLE_H Output voltage peak-to-peak ripple in Hysteretic mode   50   mV
VORIPPLE_PWM Output voltage peak-to-peak ripple in PWM mode     10 mV
LOADTR

Load transient regulation

IOUT rises or falls between 10 mA - 150 mA in 10 μs

PWM mode

 -50   50 mV
LINETR

Line transient regulation

VINBUCK2 voltage rises or falls 300 mV in 10 μs with 1 kHz rate

PWM mode

   +/- 10   mV
EFF100MA

BUCK efficiency with 100 mA load current

VINBUCK2 = 3.8 V, VO2 = 1.2 V, T = 25°C

PWM mode

   87   %

Electrical characteristics

Figure 11. BUCK2 efficiency vs. load current (VINBUCK2 = 3.8 V, VO2 = 1.2 V)
BUCK2 efficiency vs. load current
Figure 12. BUCK2 load transient (VINBUCK2 = 3.8 V, VO2 = 1.2 V, ILOAD 10 mA - 150 mA)
BUCK2 load transient
Figure 13. VO2 vs. temperature (VINBUCK2 = 3.8 V, VO2 = 1.2 V)
VO2 vs. temperature
Figure 14. Mode transition from hysteretic to PWM (VINBUCK2 = 3.8 V, VO2 = 1.2 V, I_OUT = 10 mA)
Mode transition from hysteretic to PWM

BUCK3

BUCK3 is not enabled by default.

BUCK3 is controlled through the TWI and is by default set to Hysteretic mode. It can supply up to 550 mA in PWM mode and up to 10 mA in Hysteretic mode. The output voltage is controlled by a DAC and can be programmed in 25 mV steps between 0.5 V and 3.3 V.

BUCK3 must start up in Hysteretic mode, meaning that the load must not exceed 10 mA during startup. It is strongly recommended to set BUCK3 to PWM once it has started.

The following registers control BUCK3:
Table 7. BUCK3 control registers
Register Description
BUCK3.VOUT Output voltage setting (for both modes)
BUCK3.SEL.DAC Enabling the DAC
TASKS_START_BUCK3 Enabling the BUCK
BUCK3.CONF.PWM.MODE Entering PWM mode
TASKS_STOP_BUCK3 Disabling the BUCK

The (decimal) code for a given output voltage VO3 can be calculated using equation Code = (VO3 - 0.5 V) / 0.025 V.

Note: Dynamic voltage adjustment while BUCK3 is operating is not recommended.

Electrical specification

Table 8. BUCK3 electrical specification
Symbol Description Min. Typ. Max. Units
VINBUCK3 Regulator input voltage 3.0   5.5 V
VO3 Regulator output voltage range 0.5   3.3 V
VO3STEP Output voltage programming step   25   mV
VDO3

Drop out voltage (IOUT = 500 mA)

   150   mV
VACC

Output voltage accuracy

Average voltage, not including ripple or transients

PWM mode

 -6   2 %
IOUT_PWM Output current range, PWM mode 0   550 mA
IOUT_H Output current range, Hysteretic mode 0   10 mA
VO3RIPPLE_H Output voltage peak-to-peak ripple in Hysteretic mode   50   mV
VO3RIPPLE_PWM Output voltage peak-to-peak ripple in PWM mode over output current range and VINBUCK - VO3 > 1.0 V     25 mV
LOADTR

Load current transient

Load current Trise=Tfall=1 μs, VO3=1.3 V, Iload 30 mA - 150 mA

PWM mode

 -50   50 mV
LINETR

Line transient regulation

VINBUCK3 voltage rises or falls 300 mV in 10 μs with 1 kHz rate

PWM mode

   +/-15   mV
EFF200MA

BUCK3 efficiency with 200 mA load current

VINBUCK3 = 3.8 V, VO3 = 3.3 V, T = 25°C

PWM mode

   93   %
tSTART Startup time (VO3 = 3.3 V)     200 μs

Electrical characteristics

Figure 15. BUCK3 efficiency vs. load current (VINBUCK3 = 3.8 V, VO3 = 3.3 V)
BUCK3 efficiency vs. load current (VO3 = 3.3 V)
Figure 16. BUCK3 load transient (VINBUCK3 = 3.8 V, VO3 = 1.3 V, Iload 30 mA - 150 mA)
BUCK3 load transient
Figure 17. V03 vs. temperature (VINBUCK3 = 3.8 V, VO3 = 3.3 V)
V03 vs. temperature (VO3 = 3.3 V)

LDO0

LDO0 is a general purpose linear low dropout regulator. It is fully controlled by the host system through TWI.

LDO0 output voltage is set in register LDO0.VOUT and can be 1.8 V up to 3.3 V in 300 mV steps. The default voltage is 3 V. It supports a load current of up to 30 mA and is set in register TASKS_START_LDO0.

Electrical specification

Table 9. LDO0 electrical specification
Symbol Description Min. Typ. Max. Units
VINLDO0 Regulator input voltage 3.0   5.5 V
VLDO0 Regulator output voltage   1.8, 2.1, 2.41, 2.7, 3.0, 3.3   V
VACCLDO0 Output voltage accuracy -3   3 %
VDO

Dropout voltage

IOUT = 30 mA

   200   mV
IOUT Load current output range 0   30 mA
LOADTR

Load transient regulation

IOUT rises or falls between 0 mA - 30 mA in 10 μs

   +/-25   mV
LINETR

Line transient regulation

VINLDO0 voltage rises or falls 300 mV in 10 μs with 1 kHz rate

   +/-10   mV
IQ

Quiescent current, no load

At least one BUCK[0..2] running in PWM mode

   80   μA
tSTART Startup time (VLDO0 = 3.3 V)     500 μs

Electrical characteristics

Figure 18. LDO0 load transient (VLDO0 = 3.0 V, Iload 0 mA - 30 mA)
LDO0 load transient

LDO1

LDO1 is a general purpose linear low dropout regulator. It is fully controlled by the host system through TWI.

LDO1 delivers 1.8 V output voltage with very low quiescent power consumption. It supports up to 15 mA load currents that can be set in register TASKS_START_LDO1.

Electrical specification

Table 10. LDO1 electrical specification
Symbol Description Min. Typ. Max. Units
VINLDO1 Regulator input voltage 3.0   5.5 V
VLDO1 Regulator output voltage 1.62 1.8 1.98 V
IOUT Average load current output range 0   15 mA
LOADTR

Load transient regulation

IOUT rises or falls between 0 mA - 15 mA in 10 μs

   +/-10   mV
LINETR

Line transient regulation

VINLDO1 voltage rises or falls 300 mV in 10 μs with 1 kHz rate

   +/-10   mV
IQ

Quiescent current, no load

All active BUCKs (BUCK[0..2]) running in Hysteretic mode

   1.6   μA

Quiescent current, no load

At least one BUCK[0..2] running in PWM mode

   22   μA
tSTART Startup time     300 μs

Electrical characteristics

Figure 19. LDO1 load transient (VLDO1 = 1.8 V, Iload 0 mA - 15 mA)
LDO1 load transient

Power-on reset

When VIN rises above VINVTH1_RISE, a power-on reset (POR) occurs. The chip starts up when the ENABLE pin is HIGH.

When VIN falls below VINVTH1_FALL, the chip shuts down.

Electrical specification

Table 11. Power-on reset electrical specification
Symbol Description Min. Typ. Max. Units
VINVTH1_RISE Threshold voltage for rising supply 2.8 2.9 3.0 V
VINVTH1_FALL Threshold voltage for falling supply 2.7 2.8 2.9 V