Rainbow Electronics MAX17036 - Manual (Page 14)

MAX17030/MAX17036
1/2/3-Phase Quick-PWM
IMVP-6.5 VID Controllers
14 ______________________________________________________________________________________
Pin Description (continued)
PIN NAME FUNCTION
This low-voltage logic input indicates power usage and sets the operating mode together
with DPRSLPVR as shown in the truth table below. While DPRSLPVR is low, if PSI is forced low, the
controller is immediately set to (N-1)-phase forced-PWM mode. The controller returns to N-phase
forced-PWM mode when
PSI is forced high.
The controller is in N-phase skip mode during startup including boot mode, but is in N-phase
forced-PWM mode during the transition from boot mode to VID mode, during soft-shutdown,
irrespective of the DPRSLPVR and
PSI logic levels. However, if phases 2 and 3 are disabled by
connecting CSP2, CSP3 to VCC, then only phase 1 is active in the above modes.
DPRSLPVR PSI MODE
15 PSI
1
0
0 X
0
1
Very low current (1-phase skip)
Intermediate power potential (N-1-phase PWM)
Max power potential (full-phase PWM: N-phase or 1 phase as set by user
at CSP2, CSP3)
16 TON
Switching Frequency Setting Input. An external resistor between the input power source and this
pin sets the switching frequency according to the following equation:
f SW = 1/(C TON x (R TON + 6.5k
))
where C TON = 16.26pF.
The external resistor must also satisfy the requirement [V IN(MIN) /R TON ]  10µA where V IN(MIN) is
the minimum V IN value expected in the application.
TON is high impedance in shutdown.
17 CLKEN
Clock Enable CMOS Push-Pull Logic Output Powered by V
3P3
. This inverted logic output indicates
when the output voltage sensed at FB is in regulation. CLKEN is forced high in shutdown and during
soft-start and soft-stop transitions. CLKEN is forced low during dynamic VID transitions and for an
additional 20µs after the transition is completed. CLKEN is the inverse of PWRGD, except for the 5ms
PWRGD startup delay period after CLKEN is pulled low. See the startup timing diagram (Figure 9). The
CLKEN upper threshold is blanked during any downward output-voltage transition that happens when
the controller is in skip mode, and stays blanked until the slew-rate-controlled internal-transition-
related PWRGD blanking period is complete and the output reaches regulation.
18 PWRGD
Open-Drain Power-Good Output. After output-voltage transitions, except during power-up and power-
down, if FB is in regulation, then PWRGD is high impedance.
PWRGD is low during startup, continues to be low while the output is at the boot voltage, and stays
low until 5ms (typ) after
CLKEN goes low, after which it starts monitoring the FB voltage and goes
high if FB is within the PWRGD threshold window.
PWRGD is forced low during soft-shutdown and while in shutdown. PWRGD is forced high
impedance whenever the slew-rate controller is active (output-voltage transitions), and continues
to be forced high impedance for an additional 20µs after the transition is completed.
The PWRGD upper threshold is blanked during any downward output-voltage transition that
happens when the controller is in skip mode, and stays blanked until the slew-rate-controlled
internal-transition-related PWRGD blanking period is complete and the output reaches regulation.
A pullup resistor on PWRGD causes additional finite shutdown current.
19 DRSKP
Driver Skip Control Output. Push/pull logic output that controls the operating mode of the skip-
mode driver IC.
DRSKP swings from V
DD to GND. When DRSKP is high, the driver ICs operate in
forced-PWM mode. When DRSKP is low, the driver ICs enable their zero-crossing comparators and
operate in pulse-skipping mode. DRSKP goes low at the end of the soft-shutdown sequence,
instructing the external drivers to shut down.