LTC3872ETS8#TRMPBF Linear Technology, LTC3872ETS8#TRMPBF Datasheet - Page 10

• Manufacturer Part Number: LTC3872ETS8#TRMPBF
• Description: IC DC/DC CNTRLR TSOT23-8
• Manufacturer: Linear Technology
• Type: Step-Up (Boost)r

Specifications of LTC3872ETS8#TRMPBF

• Internal Switch(s): No
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.2 ~ 60 V
• Current - Output: 10A
• Frequency - Switching: 550kHz
• Voltage - Input: 2.75 ~ 9.8 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: TSOT-23-8, TSOT-8
• Primary Input Voltage: 9.8V
• No. Of Outputs: 1
• Output Voltage: 60V
• No. Of Pins: 8
• Operating Temperature Range: -40°C To +85°C
• Msl: MSL 1 - Unlimited
• Supply Voltage Range: 2.75V To 9.8V
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Other names: LTC3872ETS8#TRMPBF; LTC3872ETS8#TRMPBFTR

to 30V or less, and the switch node can ring during the
turn-off of the MOSFET due to layout parasitics. Check
the switching waveforms of the MOSFET directly across
the drain and source terminals using the actual PC board
layout (not just on a lab breadboard!) for excessive ringing.
During the switch on-time, the control circuit limits the
maximum voltage drop across the power MOSFET to about
270mV, 100mV and 170mV at low duty cycle with IPRG
tied to V
inductor current is therefore limited to (270mV, 170mV and
100mV)/R
The relationship between the maximum load current, duty
cycle and the R
V
power MOSFET. V
100mV. It is reduced with increasing duty cycle as shown
in Figure 3. The r
efficient of the R
0.4%/°C. Figure 4 illustrates the variation of normalized
R
Another method of choosing which power MOSFET to
use is to check what the maximum output current is for a
given R
in discrete values.
It is worth noting that the 1 – D
I
wide input range to experience a dramatic range of maxi-
mum input and output current. This should be taken into
consideration in applications where it is important to limit
the maximum current drawn from the input supply.
Voltage on the NGATE pin should be within –0.3V to
(V
V
tional Diagram. This is especially important in case of
LTC3872
applicaTions inForMaTion
10
O(MAX)
SENSE(MAX)
IN
DS(ON)
IN
R
I
O(MAX)
+ 0.3V can damage internal MOSFET driver, see Func-
+ 0.3V) limits. Voltage stress below –0.3V and above
DS(ON)
DS(ON)
and R
over temperature for a typical power MOSFET.
IN
DS(ON)
= V
, GND, or left floating respectively. The peak
≤ V
is the maximum voltage drop across the
, since MOSFET on-resistances are available
SENSE(MAX)
DS(ON)
SENSE(MAX)
DS(ON)
DS(ON)
SENSE(MAX)
depending on the status of the IPRG pin.
T
term accounts for the temperature co-
can cause boost converters with a
of the power MOSFET is:
of the MOSFET, which is typically
•
•

 
is typically 270mV, 170mV and

 
1+
1+
MAX
χ
2
χ
2
1– D

 
1– D

 
• R
relationship between
•I
O(MAX)
MAX
DS(ON)
MAX
• ρ
• ρ
T
T
driving MOSFETs with relatively high package inductance
(DPAK and bigger) or inadequate layout. A small Schottky
diode between NGATE pin and ground can prevent nega-
tive voltage spikes. Two small Schottky diodes can inhibit
positive and negative voltage spikes (Figure 5).
Figure 3. Maximum SENSE Threshold Voltage vs Duty Cycle
Figure 4. Normalized R
300
250
200
150
100
LTC3872
2.0
1.5
1.0
0.5
50
GND
0
0
V
– 50
NGATE
IN
1
SW
20
JUNCTION TEMPERATURE (°C)
0
IPRG = FLOAT
IPRG = HIGH
IPRG = LOW
DUTY CYCLE (%)
Figure 5
40
DS(ON)
50
LTC3872
60
GND
V
NGATE
IN
vs Temperature
SW
100
80
3872 G03
3872 F04
3872 F04
100
150
3872fb