IR3856WMTR1PBF International Rectifier, IR3856WMTR1PBF Datasheet - Page 17

• Manufacturer Part Number: IR3856WMTR1PBF
• Description: IC REG SYNC BUCK 6A 17-QFN
• Manufacturer: International Rectifier
• Series: SupIRBuck™r
• Type: Step-Down (Buck)r

Specifications of IR3856WMTR1PBF

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 0.7 ~ 14.4 V
• Current - Output: 6A
• Frequency - Switching: 225kHz ~ 1.65MHz
• Voltage - Input: 1.5 ~ 16 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 17-PowerVQFN
• Power - Output: 1.3W
• Part Status: Active
• Package: PQFN / 4 x 5
• Circuit: Single Output
• Iout (a): 6
• Switch Freq (khz): 0 - 750
• Input Range (v): 1.5 - 16
• Output Range (v): 0.7 - 0.9*Vin
• Ocp Otp Uvlo Pre-bias Soft Start And: PGOOD + EN + SEQ + OVD
• Server Storage: Yes
• Routers Switches: Yes
• Base Station Telecom: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: IR3856WMTR1PBFTR

Minimum on time Considerations
The minimum ON time is the shortest amount of
time for which the Control FET may be reliably
turned on, and this depends on the internal
timing delays. For the IR3856W, the typical
minimum on-time is specified as 50 ns.
Any design or application using the IR3856W
must ensure operation with a pulse width that is
higher than this minimum on-time and preferably
higher than 100 ns. This is necessary for the
circuit to operate without jitter and pulse-
skipping, which can cause high inductor current
ripple and high output voltage ripple.
In any application that uses the IR3856W, the
following condition must be satisfied:
The minimum output voltage is limited by the
reference voltage and hence V
Therefore, for V
Therefore, at the maximum recommended input
voltage 21V and minimum output voltage, the
converter should be designed at a switching
frequency that does not exceed 330 kHz.
Conversely, for operation at the maximum
recommended operating frequency 1.2 MHz and
minimum output voltage, any voltage above
5.83V may not be stepped down reliably without
pulse-skipping.
Rev 8.0
∴
∴
V
∴
∴
in
t
V
on
V
t
×
in
on
t
(min)
in
on
F
×
(min)
×
s
out(min)
F
=
=
F
s
≤
≤
V
s
F
D
≤
≤
in
V
t
s
V
≤
on
t
V
out
100
out
×
on
0.7
= 0.7 V,
t
in
V
on
V
(min)
(min)
F
out
×
out
(min)
s
ns
V
F
s
=
7 ×
out(min)
10
6
V/s
= 0.7 V.
Maximum Duty Ratio Considerations
A fixed off-time of 200 ns maximum is specified
for the IR3856W. This provides an upper limit on
the operating duty ratio at any given switching
frequency. It is clear that, higher the switching
frequency, the lower is the maximum duty ratio at
which the IR3856W can operate. To allow a
margin of 50 ns, the maximum operating duty
ratio in any application using the IR3856W
should still accommodate about 250 ns off-time.
Fig 10. shows a plot of the maximum duty ratio
v/s the switching frequency, with 250 ns off-time.
95
90
85
80
75
70
300
Fig. 10. Maximum duty cycle v/s switching
400
frequency.
500
600
Switching Frequency (kHz)
IR3856WMPbF
700
800
900
1000
PD-97506
1100
17
1200