NXP Semiconductors
PF4210
14-channel power management integrated circuit (PMIC) for audio/video applications
10.4.4.6 SW4
SW4 is a 1.0 A rated single phase buck regulator capable of operating in two modes.
In default mode, it operates as a normal buck regulator with a programmable output
between 0.400 V and 3.300 V. It is capable of operating in the three available
switching modes: PFM, APS, and PWM, described in Table 28 and configured by the
SW4MODE[3:0] bits, as shown in Table 29.
If the system requires DDR memory termination, SW4 can be used in VTT mode. In the
VTT mode, the reference voltage tracks the output voltage of SW3A, scaled by 0.5. In
VTT mode, only the PWM switching mode is allowed. The VTT mode can be configured
by use of VTT bit in the OTP_SW4_CONFIG register.
Figure 25 shows the block diagram and the external component connections for the SW4
regulator.
VIN
SW4IN
SW4AMODE
I
SENSE
C
INSW4
CONTROLLER
SW4
SW4LX
EP
DRIVER
L
SW4
SW4AFAULT
C
OSW4
2
I C
INTERFACE
INTERNAL
COMPENSATION
I2C
Z2
SW4FB
Z1
EA
V
REF
DAC
aaa-026494
Figure 25.ꢀSW4 block diagram
10.4.4.6.1 SW4 setup and control registers
To set the SW4 in regulator or VTT mode, bit VTT of the register OTP_SW4_CONF
register in Table 135 is programmed during OTP or TBB configuration; setting bit VTT
to 1 enables SW4 to operate in VTT mode and 0 in regulator mode. See Section 10.1.2
"One time programmability (OTP)" for detailed information on OTP configuration.
In regulator mode, the SW4 output voltage is programmable from 0.400 V to 3.300 V;
however, bit SW4[6] in the SW4VOLT register is read-only during normal operation. Its
value is determined by the default configuration, or may be changed by using the OTP
registers. Once SW4[6] is set to 0, the output is limited to the lower output voltage range
from 0.400 V to 1.975 V with 25 mV increments, as determined by the SW4[5:0] bits.
Likewise, once the SW4[6] bit is set to 1, the output voltage is limited to the higher output
voltage range from 0.800 V to 3.300 V with 50 mV increments, as determined by the
SW4[5:0] bits.
To optimize the performance of the regulator, it is recommended only voltage from
2.000 V to 3.300 V be used in the high range and the lower range be used for voltage
from 0.400 V to 1.975 V.
The output voltage set point is independently programmed for normal, standby, and sleep
mode by setting the SW4[5:0], SW4STBY[5:0], and SW4OFF[5:0] bits, respectively.
However, the initial state of the SW4[6] bit is copied into bits SW4STBY[6], and
PF4210
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© NXP B.V. 2018. All rights reserved.
Data sheet: technical data
Rev. 2.0 — 14 November 2018
74 / 137
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