LT1106 Datasheet, PDF (5/8 Pages) Linear Technology – Micropower Step-Up DC/DC Converter for PCMCIA Card Flash Memory

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SELECT 12/5 (Pin 1): Tie to V_IN or logic 1 for 5V output;
tie to GND or logic 0 for 12V output.
SOFT START (Pin 2): A 0.1µF/1MΩ parallel RC from this
pin to GND provides a Soft Start function upon device
turn-on. Initially about 80µA 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.
V_CC (Pins 3, 4): Input Supply. Both pins should be tied
together. At least 1µF 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
when V_CC = 5V; low when V_CC = 3.3V.
PGND (Pins 6, 7): Power Ground. Connect to ground plane.
V_SW (Pins 9, 10, 11): Collector of Power Switch. High dV/
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.
LT1106
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
350µA. 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
1MΩ resistive divider that sets the output voltage. In
shutdown, the resistor string is disconnected and current
into this pin is reduced to < 1µA.
ON/OFF (Pin 20): Shutdown Control. When pulled below
1.5V, this pin disables the LT1106 and reduces supply
current to 10µA. All circuitry except the 3/5 comparator
is disabled in shutdown. The part is enabled when
ON/OFF is greater than 1.5V.
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