MAX17030GTL 查看數據表（PDF） - Maxim Integrated
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MAX17030GTL Datasheet PDF : 38 Pages
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1/2/3-Phase Quick-PWM
IMVP-6.5 VID Controllers
Detailed Description
Free-Running, Constant-On-Time PWM
Controller with Input Feed-Forward
The Quick-PWM control architecture is a pseudo-fixed-
frequency, constant-on-time, current-mode regulator with
voltage feed-forward (Figure 3). This architecture relies on
the output filter capacitor’s ESR to act as the current-
sense resistor, so the output ripple voltage provides the
PWM ramp signal. The control algorithm is simple: the
high-side switch on-time is determined solely by a one-
shot whose period is inversely proportional to input volt-
age, and directly proportional to output voltage or the
difference between the main and secondary inductor cur-
rents (see the On-Time One-Shot section). Another one-
shot sets a minimum off-time. The on-time one-shot
triggers when the error comparator goes low, the inductor
current of the selected phase is below the valley current-
limit threshold, and the minimum off-time one-shot times
out. The controller maintains 120° out-of-phase operation
by alternately triggering the three phases after the error
comparator drops below the output-voltage set point.
Triple 120° Out-of-Phase Operation
The three phases in the MAX17030/MAX17036 operate
120° out-of-phase to minimize input and output filtering
requirements, reduce electromagnetic interference (EMI),
and improve efficiency. This effectively lowers component
count—reducing cost, board space, and component
power requirements—making the MAX17030/MAX17036
ideal for high-power, cost-sensitive applications.
The MAX17030/MAX17036 share the current between
three phases that operate 120° out-of-phase, so the
high-side MOSFETs never turn on simultaneously dur-
ing normal operation. The instantaneous input current
of each phase is effectively reduced, resulting in
reduced input voltage ripple, ESR power loss, and RMS
ripple current (see the Input Capacitor Selection sec-
tion). Therefore, the same performance can be
achieved with fewer or less-expensive input capacitors.
+5V Bias Supply (VCC and VDD)
The Quick-PWM controller requires an external +5V
bias supply in addition to the battery. Typically, this
+5V bias supply is the notebook’s 95% efficient +5V
system supply. The +5V bias supply must provide VCC
(PWM controller) and VDD (gate-drive power), so the
maximum current drawn is:
( ) IBIAS = ICC + fSW QG(LOW) + QG(HIGH)
where ICC is provided in the Electrical Characteristics
table, fSW is the switching frequency, and QG(LOW) and
QG(HIGH) are the MOSFET data sheet’s total gate-
charge specification limits at VGS = 5V.
VIN and VDD can be connected together if the input
power source is a fixed +4.5V to +5.5V supply. If the
+5V bias supply is powered up prior to the battery sup-
ply, the enable signal (SHDN going from low to high)
must be delayed until the battery voltage is present to
ensure startup.
Switching Frequency (TON)
Connect a resistor (RTON) between TON and VIN to set
the switching period TSW = 1/fSW, per phase:
TSW = 16.26pF x (RTON + 6.5kΩ)
A 96.75kΩ to 303.25kΩ corresponds to switching peri-
ods of 167ns (600kHz) to 500ns (200kHz), respectively.
High-frequency (600kHz) operation optimizes the appli-
cation for the smallest component size, trading off effi-
ciency due to higher switching losses. Low-frequency
(200kHz) operation offers the best overall efficiency at
the expense of component size and board space.
TON Open-Circuit Protection
The TON input includes open-circuit protection to avoid
long, uncontrolled on-times that could result in an over-
voltage condition on the output. The MAX17030/
MAX17036 detect an open-circuit fault if the TON current
drops below 10µA for any reason—the TON resistor
(RTON) is unpopulated, a high resistance value is used,
the input voltage is low, etc. Under these conditions, the
MAX17030/MAX17036 stop switching (DH and DL pulled
low) and immediately set the fault latch. Toggle SHDN or
cycle the VCC power supply below 0.5V to clear the fault
latch and reactivate the controller.
On-Time One-Shot
The MAX17030/MAX17036 contain a fast, low-jitter,
adjustable one-shot that sets the high-side MOSFETs
on-time. It is shared among the three phases. The one-
shot for the main phase varies the on-time in response
to the input and feedback voltages. The main high-side
switch on-time is inversely proportional to the input volt-
age as measured by the V+ input, and proportional to
the feedback voltage (VFB):
t ON
=
TSW
(VFB + 0.075V)
VIN
The one-shot for the second phase and third phase
varies the on-time in response to the input voltage and
the difference between the main and the other inductor
currents. Two identical transconductance amplifiers
integrate the difference between the master and each
slave’s current-sense signals. The summed output is
connected to an internal integrator for each master-
slave pair, which serves as the input to the respective
slave’s high-side MOSFET TON timer.
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