MAX8688BHETG+ Maxim Integrated Products, MAX8688BHETG+ Datasheet - Page 12

• Manufacturer Part Number: MAX8688BHETG+
• Description: IC PWR SUPPLY CTRLR/MONTR 24TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8688BHETG+

• Applications: Power Supply Controller/Monitor
• Voltage - Supply: 3 V ~ 3.6 V
• Current - Supply: 6.7mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-TQFN Exposed Pad
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 3 V
• Operating Temperature Range: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Input: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

In applications where a REFIN input is not available, the
MAX8688 interfaces to the inverting input of the POL
error amplifier, the feedback node (FB), through a
resistor R
ation, the MAX8688 controls the POL voltage as mea-
sured between RS+ and RS- to 0.2% accuracy over
line, load, and temperature variations, by adjusting
DACOUT 1 LSB (0.5mV) at a time, up and down as
required. This mode of operation is termed FB mode.
Since the MAX8688 does not have control over the POL
error-amplifier reference voltage, this mode relies on
the POL soft-start setting to implement the required
soft-start time. On receipt of either an OPERATION ON
command or a turn-on signal from A3/ONOFF, the
MAX8688 commences startup operations that have
been programmed for the POL being controlled. After
the programmed t
drain ENOUT output goes active, causing the POL to
ramp up its output voltage to its target value. The soft-
start time taken by the POL to ramp from zero to its
commanded output voltage should be entered into the
MAX8688 with the t
During t
high-impedance state by keeping the S1 switch open.
This allows the voltage at DACOUT to equal that of the
FB node of the POL. At the end of the t
Digital Power-Supply Controller/Monitor
with PMBus Interface
Figure 4. REFIN Mode Timing
12
______________________________________________________________________________________
OPERATION
OUTPUT
ON_RISE
ENOUT
V
FB
POL
DAC
POL
OUT
as shown in Figure 5. In steady-state oper-
, the MAX8688 maintains DACOUT in a
ON_DELAY
ON_RISE
t
PMB_RSP
parameter.
time, the MAX8688 open-
t
CLOSE S1
Feedback (FB) Mode
ON_DELAY
ON_RISE
t
ON_RISE
TURN-ON
delay
time, the internal DAC output is initialized to the external
voltage measured on DACOUT and switch S1 is closed.
If the POL has completed its soft-start and settled down
at its output voltage, the DAC output is initialized to the
steady-state value of the POL FB voltage. Therefore,
when switch S1 is closed, the voltages on either side of
the resistor R
current flows into the FB node from DACOUT and no
perturbations are introduced to the output voltage. From
this point on, the MAX8688 adjusts the voltage at
DACOUT to provide accurate output voltage control. In
FB mode, the user is required to supply t
t
(the default values are zero), S1 closes prematurely and
cause an initial error in the voltage monitor.
On receipt of either an OPERATION OFF command or a
turn-off signal from A3/ONOFF, the MAX8688 com-
mences the shutdown operation that has been pro-
grammed for the POL being controlled. After the
programmed t
its open-drain ENOUT output, and turns off the POL.
For the FB mode, the value of R
following formula:
ON_RISE
t
PMB_RSP
t
OFF_DELAY
parameters. If those parameters are not set
FB
OFF_DELAY
are equal. Under these conditions, zero
R
TURN-OFF
FB
t
OFF_FALL
=
R
time, the MAX8688 deasserts
1
×
∆
∆
V
FB
DAC
V
O
is selected based on
ON_DELAY
and