LTC1439 查看數據表（PDF） - Linear Technology

零件编号

产品描述 (功能)

生产厂家

LTC1439

Dual High Efficiency, Low Noise, Synchronous Step-Down Switching Regulators

Linear Technology 

LTC1438/LTC1439

TYPICAL PERFORMANCE CHARACTERISTICS

Auxiliary Regulator

Sink Current Available

20

15

10

5

0

0 2 4 6 8 10 12 14 16

AUX DR VOLTAGE (V)

1438 G19

Auxiliary Regulator PSRR

70

10mA LOAD

60

50

100mA LOAD

40

30

20

10

10

100

FREQUENCY (kHz)

1000

1438 G20

PIN FUNCTIONS

VIN: Main Supply Pin. Must be closely decoupled to the

IC’s signal ground pin.

INTVCC: Output of the Internal 5V Regulator and the

EXTVCC Switch. The driver and control circuits are pow-

ered from this voltage. Must be closely decoupled to

power ground with a minimum of 2.2µF tantalum or

electrolytic capacitor. The INTVCC regulator turns off when

both RUN/SS1 and RUN/SS2 are low. Refer to the LTC1538/

LTC1539 for 5V keep-alive applications.

EXTVCC: External Power Input to an Internal Switch. This

switch closes and supplies INTVCC, bypassing the internal

low dropout regulator whenever EXTVCC is higher than

4.7V. Connect this pin to VOUT of the controller with the

higher output voltage. Do not exceed 10V on this pin. See

EXTVCC connection in Applications Information section.

BOOST 1, BOOST 2: Supplies to the Topside Floating

Drivers. The bootstrap capacitors are returned to these

pins. Voltage swing at these pins is from INTVCC to

VIN + INTVCC.

SW1, SW2: Switch Node Connections to Inductors. Volt-

age swing at these pins is from a Schottky diode (external)

voltage drop below ground to VIN.

SGND: Small-Signal Ground. Common to both control-

lers, must be routed separately from high current grounds

to the (–) terminals of the COUT capacitors.

PGND: Driver Power Ground. Connects to sources of

bottom N-channel MOSFETs and the (–) terminals of CIN.

SENSE – 1, SENSE – 2: Connects to the (–) input for the

currentcomparators.ExceptfortheLTC1438-ADJ,SENSE –

1 is internally connected to the first controller’s VOUT

sensing point. The first controller can only be used as a

3.3V or 5.0V regulator controlled by the VPROG1 pin with

the LTC1438, LTC1438X and LTC1439. The LTC1438-ADJ

Controller 1 implements a remote sensing adjustable

regulator. The second controller can be set to a 3.3V, 5.0V

or an adjustable regulator controlled by the VPROG2 pin

(see Table 1).

Table 1. Output Voltage Table

LTC1438-ADJ LTC1438/LTC1438X LTC1439

Controller 1 Adjustable Only

5V or 3.3V Only

Secondary Feedback Loop

Controller 2 Adjustable Only

Remote Sensing

POR2 Output

Adjustable Only 5V/3.3V/Adjustable

Remote Sensing Remote Sensing

POR2 Output

POR2 Output

14389fb

7

Share Link: