MAX1980ETP+ Maxim Integrated Products, MAX1980ETP+ Datasheet - Page 22

• 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

In non-CPU applications, the output capacitor selection
often depends on how much ESR is needed to maintain
an acceptable level of output ripple voltage. The output
ripple voltage of a step-down controller equals the total
inductor ripple current multiplied by the output capaci-
tor’s ESR. When operating multiphase systems out-of-
phase, the peak inductor currents of each phase are
staggered, resulting in lower output ripple voltage by
reducing the total inductor ripple current. For out-of-
phase operation, the maximum ESR to meet ripple
requirements is:
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
Figure 6. Master/Slave Current-Limit Thresholds
22
R
ESR
______________________________________________________________________________________
≤



L
η










V
IN
−
f
SW
η
V
OUT
160
140
120
100
160
140
120
100
80
60
40
20
80
60
40
20
0
0



V



0
0
RIPPLE
V
MASTER CURRENT-LIMIT VOLTAGES
SLAVE CURRENT-LIMIT VOLTAGES
vs. AVERAGE INDUCTOR CURRENT
vs. AVERAGE INDUCTOR CURRENT
OUT
V
IN
AVERAGE INDUCTOR CURRENT (A)
AVERAGE INDUCTOR CURRENT (A)
10
10



−
(
η 1
20
20
−
)
V
OUT TRIG
30
30
t
40
40




50
50
This equation may be rewritten as the single phase rip-
ple current minus a correction due to the additional
phases:
where t
delay, η is the number of phases, and K is from Table
3. When operating the MAX1980 in-phase (POL =
GND), the high-side MOSFETs turn on together, so the
output capacitors must simultaneously support the
combined inductor ripple currents of each phase.
R
V
V
R
R
V
∆I
UNADJUSTED ∆I
V
ADJUSTED ∆I
V
R
R
I
ADJ(MIN)
ESR
ITHM(HIGH)
ITHM(LOW)
CM
CM
ITHS
ITHM(HIGH)
ITHM(LOW)
DS(ON)(MIN)
DS(ON)(MIN)
ADJ
I
I
LM(PEAK)
LM(VALLEY)
- ∆I
≤
= I
TRIG
INDUCTOR
PEAK



= L
= L
I
LIMIT
LOAD MAX
= R
= R
LM(VALLEY)
LM(VALLEY)
MASTER
CONTROLLER
=
LIMIT
CS
V
CS
≤ ∆I
R
I
is the MAX1980’s trigger propagation
=
LS(PEAK)
ITHS
CM
[
I
≤ ∆I
LS(VALLEY)
(
V
INDUCTOR
OUT
LIMIT
V
(V
IN
IN
f
)
SW
= V
LIR
- V
L
ITHM(HIGH)
SLAVE
CONTROLLER
OUT
−
)
]
η η 1
(
V
(
RIPPLE
−
R
DS(ON)(MAX)
A
)
RDS



V
- 1
OUT
L
)



(
t
ON
+
t
TRIG
)


