MAX1980ETP+ Maxim Integrated Products, MAX1980ETP+ Datasheet - Page 20

• Manufacturer Part Number: MAX1980ETP+
• Description: IC CNTRLR QUICK-PWM 20-TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX1980ETP+

• Pwm Type: Controller
• Number Of Outputs: 1
• Frequency - Max: 550kHz
• Duty Cycle: 50%
• Voltage - Supply: 4 V ~ 28 V
• Buck: Yes
• Boost: No
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: 0°C ~ 85°C
• Package / Case: 20-TQFN Exposed Pad
• Frequency-max: 550kHz
• Input Voltage: 4 V to 28 V
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 100 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

where V
ically 1/10th the voltage seen at the master’s ILIM input
(V
troller’s data sheet). Connect a resistive voltage-divider
from the master controller’s internal reference to GND,
with the master’s ILIM input connected to the center tap
(Figure 5). Use 1% tolerance resistors in the divider with
10µA to 20µA DC bias current to prevent significant
errors due to the ILIM pin’s input current:
Configure the slave controller so its LIMIT output begins
to roll off after the master current-limit threshold occurs:
where V
cisely one-tenth the voltage seen at the slave’s ILIM
input (V
resistive voltage-divider from the master controller’s
internal reference to GND, with the slave’s ILIM input
connected to the center tap (Figure 5). The external
adjustment range of 400mV to 1.5V corresponds to a
current-limit threshold of 40mV to 150mV. Use 1% toler-
ance resistors in the divider with 10µA to 20µA DC bias
current to prevent significant errors due to the ILIM
pin’s input current. Reducing the current-limit threshold
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
Figure 5. Setting the Adjustable Current Limits
20
ITHM
______________________________________________________________________________________
V
ITHM
ITHS
= 0.1
ITHS
ITHS
R
V
ILIM MASTER
A
MAX1980
≥
, the slave’s current-limit threshold, is pre-
, the master’s current-limit threshold, is typ-
= 0.1
=
R
CONTROLLER
✕
20
CM
(







V
µ
V
V



SLAVE
A
LIM(MASTER)
LIMIT
REF MASTER
ILIM MASTER
R
ILIM
✕
V
DS ON MAX
ITHM HIGH
V
(
(
(
ILIM(SLAVE)
)
≤
(
)(
R
R
B
D
R
)
LIMIT
R
≤
)
)
)
C
C
LIMIT



, see the master con-
V
+
ILIM MASTER
−
∆
1
). Connect a second




I
INDUCTOR
10
R
(
B
C
µ
REF
R
R
A
A
B



)
MASTER
CONTROLLER
REF
ILIM
MAX1718
voltage lowers the sense resistor’s power dissipation,
but this also increases the relative measurement error:
Now, set the current-limit adjustment ratio (A
V
minimum on-resistance ratio (A
R
Increasing A
accuracy but also increases the current limit’s noise
sensitivity. Therefore, R
following equation:
Finally, verify that the total load on the master’s refer-
ence does not exceed 50µA:
I
ITHM(HIGH)
BIAS TOTAL
DS(ON)(MIN)
V
V
V
ITHM HIGH
ITHM LOW
ITHS
(
(
(
=
R
10
LIMIT
1
R
V
/V
)
ILIM SLAVE
C
1
)



):
)
ADJ
=
+
ITHM(LOW)
=
R
=
=
20



C



≤
10
(
10




R
1
R
R
1



µ
R
+
R
A
D
A
improves the master’s current-limit
V
A



LIMIT
R
DS ON MAX



V
REF MASTER
A
+
R
//
ILIM SLAVE
R
D
(
R
(
A
ADJ
R
(
A
R



)
V
R
B
A
R
(
LIMIT
+
B
V
+
REF
(
B
≤
) greater than the maximum to
B
REF

 ≥

//
(
)(
//
R
R
≥
R
R R
//
R
B
B
D
A
B
R
R
LIMIT
R



//
may be selected using the
LIMIT
ROS
)
≤
DS ON MAX
DS ON MIN
V
R
)
)
REF
DS ON MIN
V
LIMIT
)
−
(
ILIM SLAVE
(



R
)
RDS
(
−

 +

DS ON MIN
10
1
)(
)(
(




)
(
µ
R
)(






A
= R
D
R
V
C
REF
V
)(
)
)
REF
)
+
DS(ON)(MAX)
)
R
D
)

 ≤ 50µ

ADJ
A
=
/