MAX17021 Evaluation Kit
Setting the Output Voltage
The MAX17021 has an internal digital-to-analog con-
verter (DAC) that programs the output voltage. The out-
put voltage can be digitally set from 0 to 1.5000V
(Table 2) from the D0–D6 pins. There are two different
ways of setting the output voltage:
1) Drive the external VID0–VID6 inputs (all SW1
positions are off). The output voltage is set by dri-
ving VID0–VID6 with open-drain drivers (pullup
resistors are included on the board) or 3V/5V CMOS
output logic levels.
Table 1. MAX17021 Operating Mode Truth Table
INPUTS
SHDN DPRSTP DPRSLPVR
SW2 SW2
SW2
(1, 10) (5, 6)
(2, 9)
PSI
SW2
(3, 8)
PHASE
OPERATION*
OPERATING MODE
GND
X
Rising X
High High
High High
High Low
High High
Falling X
High
X
X
X
Low
Low
High
High
X
X
X
X
High
Low
X
X
X
X
Disabled
Low-Power Shutdown Mode. DL1 and DL2 are forced low and the
controller is disabled. The supply current drops to 1µA (max).
Multiphase
Pulse Skipping
1/8 RTIME
Slew Rate
Startup/Boot. When SHDN is pulled high, the MAX17021 begins the
startup sequence. The controller enables the PWM controller and
ramps the output voltage up to the boot voltage.
Multiphase
Forced-PWM
Normal RTIME
Slew Rate
Full Power. The no-load output voltage is determined by the selected
VID DAC code (D0–D6, Table 2).
1-Phase
Forced-PWM
Normal RTIME
Slew Rate
Intermediate Power. The no-load output voltage is determined by the
selected VID DAC code (D0–D6, Table 2). When PSI is pulled low, the
MAX17021 immediately disables phase 2. DH2 and DL2 are pulled low.
1-Phase Pulse
Skipping
Normal RTIME
Slew Rate
Deeper Sleep Mode. The no-load output voltage is determined by the
selected VID DAC code (D0–D6, Table 2). When DPRSLPVR is pulled
high, the MAX17021 immediately enters 1-phase pulse-skipping
operation allowing automatic PWM/PFM switchover under light loads.
The PWRGD and CLKEN upper thresholds are blanked during
downward transitions. DH2 and DL2 are pulled low.
1-Phase Pulse
Skipping
1/4 RTIME Slew
Rate
Deeper Sleep Slow Exit Mode. The no-load output voltage is
determined by the selected VID DAC code (D0–D6, Table 2).
When DPRSTP is pulled high while DPRSLPVR is already high, the
MAX17021 remains in one-phase pulse-skipping operation, allowing
automatic PWM/PFM switchover under light loads, but reduces its
slew rate to 1/4 of normal.
Multiphase
Forced-PWM
1/8 RTIME
Slew Rate
Shutdown. When SHDN is pulled low, the MAX17021 immediately
pulls PWRGD and PHASEGD low, CLKEN becomes high impedance,
all enabled phases are activated, and the output voltage is ramped
down to ground. Once the output reaches 0V, the controller enters the
low-power shutdown state.
Disabled
Fault Mode. The fault latch has been set by the MAX17021 UVP or
thermal-shutdown protection, or by the OVP protection. The controller
remains in fault mode until VCC power is cycled or SHDN toggled.
*Multiphase operation = All enabled phases active.
X = Don’t care.
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