LTM4600HVEV#PBF Linear Technology, LTM4600HVEV#PBF Datasheet - Page 12

• Manufacturer Part Number: LTM4600HVEV#PBF
• Description: IC DC/DC UMODULE 10A 104-LGA
• Manufacturer: Linear Technology
• Series: µModuler
• Type: Point of Load (POL) Non-Isolatedr

Specifications of LTM4600HVEV#PBF

• Design Resources: LTM4600HV Spice Model
• Output: 0.6 ~ 5 V
• Number Of Outputs: 1
• Power (watts): 50W
• Mounting Type: Surface Mount
• Voltage - Input: 4.5 ~ 28 V
• Package / Case: 104-LGA
• 1st Output: 0.6 ~ 5 VDC @ 10A
• Size / Dimension: 0.59" L x 0.59" W x 0.11" H (15mm x 15mm x 2.8mm)
• Power (watts) - Rated: 50W
• Operating Temperature: -40°C ~ 85°C
• Efficiency: 92%
• Dc To Dc Converter Type: Step Down
• Pin Count: 104
• Input Voltage: 28V
• Output Voltage: 0.6 to 5V
• Switching Freq: 850KHz
• Output Current: 10A
• Package Type: LGA
• Output Type: Adjustable
• Switching Regulator: Yes
• Mounting: Surface Mount
• Input Voltage (min): 4.5V
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• 3rd Output: -
• 2nd Output: -
• Lead Free Status / Rohs Status: Compliant

APPLICATIONS INFORMATION
LTM4600HV
After the controller has been started and given adequate
time to charge up the output capacitor, C
short-circuit timer. After the RUN/SS pin charges above 4V,
if the output voltage falls below 75% of its regulated value,
then a short-circuit fault is assumed. A 1.8μA current then
begins discharging C
the RUN/SS pin drops to 3.5V, then the controller turns
off both power MOSFETs, shuting down the converter
permanently. The RUN/SS pin must be actively pulled
down to ground in order to restart operation.
The over-current protection timer requires the soft-start
timing capacitor C
that the output is in regulation by the time C
the 4V threshold. In general, this will depend upon the size
of the output capacitance, output voltage and load current
characteristic. A minimum external soft-start capacitor
can be estimated from:
Generally 0.1μF is more than suffi cient.
Since the load current is already limited by the current
mode control and current foldback circuitry during a
shortcircuit, over-current latchoff operation is NOT always
needed or desired, especially the output has large amount
of capacitance or the load draw huge current during start
up. The latchoff feature can be overridden by a pull-up
current greater than 5μA but less than 80μA to the RUN/SS
pin. The additional current prevents the discharge of C
during a fault and also shortens the soft-start period. Us-
ing a resistor from RUN/SS pin to V
12
C
SS_EXT
+ 1000pF > C
SS
SS
be made large enough to guarantee
. If the fault condition persists until
OUT
• V
OUT
IN
(10
is a simple solution
–3
SS
SS
[F / V
is used as a
has reached
S
])
SS
to defeat latchoff. Any pull-up network must be able to
maintain RUN/SS above 4V maximum latchoff threshold
and overcome the 4μA maximum discharge current. Figure
3 shows a conceptual drawing of V
short circuit.
1.5V
SWITCHING
R
V
STARTS
RUN/SS
Figure 3. RUN/SS Pin Voltage During Startup and
Short-Circuit Protection
Figure 4. Defeat Short-Circuit Latchoff with a Pull-Up
Resistor to V
IN
OF I
3V
SOFT-START
CLAMPING
L
RELEASED
V
RUN/SS
4V
PGND SGND
IN
LTM4600HV
IN
SHORT-CIRCUIT
LATCH ARMED
4600hv F04
V
O
V
RUN/SS
RECOMMENDED VALUES FOR RUN/SS
OVERLOAD
10.8V TO 13.8V
HAPPENS
OUTPUT
4.5V TO 5.5V
24V TO 28V
V
IN
RUN
during startup and
SHORT-CIRCUIT
R
75%V
LATCHOFF
RUN/SS
150k
500k
50k
O
4600hvfd
4600hv F03
3.5V
t
t