MAX8688ALETG+ Maxim Integrated Products, MAX8688ALETG+ Datasheet - Page 14

• Manufacturer Part Number: MAX8688ALETG+
• Description: IC PWR SUPPLY CTRLR/MONTR 24TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8688ALETG+

• 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

Digital Power-Supply Controller/Monitor
with PMBus Interface
ISN+ and ISN- are the inputs of the MAX8688 current-
sense amplifier. These pins may be connected to a cur-
rent-sense element such as a current-sense resistor, as
shown in Figures 3 and 5. The voltage proportional to
the sensed current is suitably filtered by an internal
200Ω resistor and external capacitor connected to
ISN_C and is multiplexed to a 12-bit ADC that uses an
accurate internal reference voltage. A scale factor can
be programmed with an IOUT_SCALE PMBus com-
mand to translate the sensed voltage information to the
current. The MAX8688 accommodates a current-sense
range of +40mV/-10mV across the ISN+ and ISN-
inputs. The common-mode voltage range for the cur-
rent-sense signal can be between 0 and 5.5V. When a
Figure 6. Feedback Mode Timing
14
OPERATION
OUTPUT
______________________________________________________________________________________
ENOUT
V
DAC
POL
POL
OUT
IN FB MODE, t
POL_RISE
t
PMB_RSP
AND t
POL_FALL
IMPEDANCE
t
ON_DELAY
HIGH-
ARE NOT CONTROLLED BY THE MAX8688 AND ARE DEPENDENT ON POL IMPLEMENTATION.
Current Sensing
t
POL_RISE
t
TURN-ON
ON_RISE
CLOSE S1
negative current is sensed by the MAX8688, FLT is
asserted indicating a negative fault current flow into the
POL output.
The DC resistance of the output inductor (DCR) in a
switch-mode power supply can also function as a current-
sense element, as shown in Figure 7. The RC filter formed
by R
times larger than the Lo/DCR time constant. Under these
conditions, the DC voltage across C
uct of the average current flowing through the output
inductor, essentially the output load current and the DCR.
The resistor R
sensing path as shown, to cancel the effect of the input
bias current voltage drop across R
t
PMB_RSP
S
and C
t
OFF_DELAY
OPEN S1
S
is designed with a time constant of about 10
BIAS
equal to R
t
POL_FALL
TURN-OFF
t
OFF_FALL
S
is placed in the current-
S
.
S
IMPEDANCE
is equal to the prod-
HIGH-