LTC3711 Datasheet, PDF (15/24 Pages) Linear Technology – 5-Bit Adjustable, Wide Operating Range, No RSENSE

LTC3711
APPLICATIO S I FOR ATIO
Output Voltage Programming
The output voltage is digitally set to levels between 0.900V
and 2.000V using the voltage identification (VID) inputs
VID0-VID4. An internal 5-bit DAC configured as a preci-
sion resistive voltage divider sets the output voltage in
increments according to Table 1. The VID codes are
compatible with Intel Mobile Pentium III processor speci-
fications. Each VID input is pulled up by an internal 2.5µA
current source from the INTV_CC supply and includes a
series diode to prevent damage from VID inputs that
exceed the supply.
INTV_CC Regulator
An internal P-channel low dropout regulator produces the
5V supply that powers the drivers and internal circuitry
within the LTC3711. The INTV_CC pin can supply up to
50mA RMS and must be bypassed to ground with a
minimum of 4.7µF low ESR tantalum capacitor. Good
bypassing is necessary to supply the high transient cur-
rents required by the MOSFET gate drivers. Applications
using large MOSFETs with a high input voltage and high
frequency of operation may cause the LTC3711 to exceed
its maximum junction temperature rating or RMS current
rating. Most of the supply current drives the MOSFET
gates unless an external EXTV_CC source is used. In con-
tinuous mode operation, this current is I_GATECHG = f(Q_g(TOP)
+ Q_g(BOT)). The junction temperature can be estimated
from the equations given in Note 2 of the Electrical
Characteristics. For example, the LTC3711CGN is limited
to less than 14mA from a 30V supply:
T_J = 70°C + (14mA)(30V)(130°C/W) = 125°C
For larger currents, consider using an external supply with
the EXTV_CC pin.
Table 1. VID Output Voltage Programming
VID4
VID3
VID2
VID1
VID0 V_OUT (V)
0
0
0
0
0
2.000V
0
0
0
0
1
1.950V
0
0
0
1
0
1.900V
0
0
0
1
1
1.850V
0
0
1
0
0
1.800V
0
0
1
0
1
1.750V
0
0
1
1
0
1.700V
0
0
1
1
1
1.650V
0
1
0
0
0
1.600V
0
1
0
0
1
1.550V
0
1
0
1
0
1.500V
0
1
0
1
1
1.450V
0
1
1
0
0
1.400V
0
1
1
0
1
1.350V
0
1
1
1
0
1.300V
0
1
1
1
1
*
1
0
0
0
0
1.275V
1
0
0
0
1
1.250V
1
0
0
1
0
1.225V
1
0
0
1
1
1.200V
1
0
1
0
0
1.175V
1
0
1
0
1
1.150V
1
0
1
1
0
1.125V
1
0
1
1
1
1.100V
1
1
0
0
0
1.075V
1
1
0
0
1
1.050V
1
1
0
1
0
1.025V
1
1
0
1
1
1.000V
1
1
1
0
0
0.975V
1
1
1
0
1
0.950V
1
1
1
1
0
0.925V
1
1
1
1
1
**
Note: *, ** represent codes without a defined output voltage as specified by
Intel. The LTC3711 interprets these codes as valid inputs and ^{produces output}
voltages as follows: [01111] = 1.250V, [11111] = 0.900V.
3711f
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