LM3464MH National Semiconductor, LM3464MH Datasheet - Page 17

• Manufacturer Part Number: LM3464MH
• Description: IC, LED DRIVER, BUCK, 28TSSOP
• Manufacturer: National Semiconductor

Specifications of LM3464MH

• No. Of Outputs: 4
• Input Voltage: 12V To 80V
• Driver Case Style: TSSOP
• Svhc: No SVHC (15-Dec-2010)
• No. Of Pins: 28
• Operating Temperature Range: -40°C To +125°C
• Topology: Linear
• Efficiency: 98%
• Led Driver Application: Streetlights, Solid State Lighting Solutions
• Dimming Control Type: PWM / Analogue
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS WITH HIGH RAIL VOLTAGE
The normal operation voltage of the LM3464 and LM3464A
are rated to 80V and 95V respectively, applying voltage over
the operation voltage limit to the LM3464/64A can damage
the device permanently. In applications that the rail voltage is
higher than the operation voltage limited of the device (80V
for LM3464, 95V for LM3464A), voltage clamping circuits
must be added externally to ensure the voltage limits of all the
pins of the LM3464/64A are not violated. Figure 13 shows a
typical application circuit with 150V peak rail voltage.
In figure 13, Z
ing the DRx pin voltage and input voltage (VIN pin) of the
1
, Z
2
FIGURE 13. Additional Voltage Clamping Circuits for V
, Z
3
, Z
4
and Z
IN
are zener diodes for clamp-
17
LM3464/64A. The reverse voltage of the zener diodes must
be below 80V for LM3464 and 95V for LM3464A. The resis-
tors R
ing the voltage difference between the clamping voltage of the
zener diodes and the rail voltage.
Calculating the Values of Z
The resistance of the R
ing to the reverse current of the zener diode and input current
of the DRx pins of the LM3464/64A to secure the allowable
pin voltages are not violated. For instant, the DRx pins are
required to clamp at 75V and a 500mW/75V zener diode
CMHZ5267B from Central Semiconductor is used. The re-
DR1
RAIL(peak)
, R
DR2
, R
> 80V/95V (LM3464/64A)
DR3
, R
DRx
DR4
must be properly selected accord-
and R
x
and R
IN
are resistors for absorb-
DRx
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