LTC3889 datasheet(69/118 Pages) AD

69 / 118 page

LTC3888/LTC3888-1/

LTC3888-2

Rev. B

For more information www.analog.com

INTERNAL REGULATOR OUTPUTS

The INTVCC pin provides supply current for much of the

internal LTC3888 analog circuitry at a nominal value of

5.2V. The LTC3888 features an internal linear regulator

that can be used to supply 5.2V to INTVCC from the pri-

mary VIN supply. At lower supply voltages, the LTC3888

will also accept an external 5V supply attached to this pin

if VIN and INTVCC are shorted. If the internal 5.2V LDO

is used, INTVCC must be bypassed to GND with a low

ESR X5R or X7R ceramic capacitor with a value between

1µF and 4.7μF. If an external 5V source supplies VIN and

INTVCC, a local low ESR bypass capacitor with a value

between 0.01μF and 0.1μF should be placed directly

between the shorted power pins and GND.

INTVCC powers secondary internal 3.3V and 2.5V LDOs

whose outputs are present on VDD33 and VDD25, respec-

tively. The 3.3V supply provides power for internal aux-

illary circuits, and the 2.5V supply provides power for

much of the internal processor logic on the LTC3888.

Both of these LDO outputs should be bypassed directly to

GND with a low ESR X5R or X7R ceramic capacitor with

a value of 1μF or greater.

Do not draw any external system current from these LDO

supplies beyond that required for specific LTC3888 con-

figuration or load/pull-up resistors.

IC JUNCTION TEMPERATURE

The user must ensure that the maximum rated junction

temperature is not exceeded under all operating condi-

tions. The thermal resistance of the LTC3888 package

(θJA) is 36°C/W, provided the exposed pad is in good

thermal contact with the PCB. The actual thermal resis-

tance in the application will depend on forced air cooling

and other heat sinking means, especially the amount of

copper on the PCB to which the LTC3888 is attached. The

following formula may be used to estimate the maximum

average power dissipation PD (in watts) of the LTC3888.

PD = VIN(.03 + IEXT + IRC25)

APPLICATIONS INFORMATION

Table 12. Resistor Programming of MFR_ADDRESS

RCONFIG (kΩ)

ASEL1

ASEL0

DEVICE ADDRESS BITS[6:4]

DEVICE ADDRESS BITS[3:0]

BINARY

HEX

BINARY

HEX

OPEN

from EEPROM

11.8

1111

10.2

1110

9.31

1101

8.66

1100

7.87

1011

7.15

1010

6.49

1001

5.9

1000

5.11

0111

4.42

0110

3.74

0101

3.09

0100

2.43

0011

1.74

0010

1.02

0001

GND

0000

LTC3889 Datasheet(PDF) 69 Page - Analog Devices

LTC3889 Datasheet(HTML) 69 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL