5

LT1106

PI FU CTIO S

tie to GND or logic 0 for 12V output.

SOFT START (Pin 2): A 0.1

µF/1MΩ parallel RC from this

pin to GND provides a Soft Start function upon device

turn-on. Initially about 80

µA will flow from the pin into the

capacitor. When the voltage at the pin reaches approxi-

mately 0.4V, current ceases flowing out of the pin. See

Applications Information section.

together. At least 1

µF input bypass capacitance is re-

quired. More capacitance reduces ringing on the supply

line.

3/5 (Pin 5): Supply Comparator Output. This pin provides

logic output indicating the value of the input supply. High

PGND (Pins 6, 7): Power Ground. Connect to ground plane.

dt present on this pin. To minimize radiated noise keep

layout short and direct.

GND (Pin 13): Signal Ground. Connect of ground plane.

VPP VALID (Pin 14): This pin provides a logic signal

indicating that ouput voltage is greater than 11.4V. Active

low with internal 200k pull-up resistor.

G1, G2 (Pins 16, 15): External MOSFET Gate Drives. When

VPP1 or VPP2 is greater than 11.7V, G1 or G2 is driven to

about 0.8V. When VPP1 or VPP2 is less than 11.7V, the

drives assume a high impedance state pulled up to the

AVPP pin through an internal 100k resistor.

VPP1, VPP2 (Pins 18, 17): Programming Power Inputs.

The LT1106 senses both VPP1 and VPP2 supplies at the

PCMCIA card socket. If VPP1 or VPP2 is greater than 11V,

the LT1106 operates in “Doze” Mode — the switching

regulator turns off and the drive to external P-channel

MOSFETs turns on. Supply current in Doze Mode is about

350

µA. Input current into VPP1 and VPP2 is about 1µA

when the device is shut down.

AVPP (Pin 19): Output Sense Pin. This pin connects to a

1M

Ω resistive divider that sets the output voltage. In

shutdown, the resistor string is disconnected and current

into this pin is reduced to < 1

µA.

ON/OFF (Pin 20): Shutdown Control. When pulled below

1.5V, this pin disables the LT1106 and reduces supply

current to 10

µA. All circuitry except the 3/5 comparator

is disabled in shutdown. The part is enabled when

ON/OFF is greater than 1.5V.