Features

• Fully Compliant with Intel 5-Bit Mobile (LTC1699-80) and Desktop VRM8.4 (LTC1699-81) and VRM9.0 (LTC1699-82) VID Specificatio
• Precision ±0.35% Programmable Resistor Divider for Use with 0.8V Referenced DC/DC Converters
• Two Different Divider Settings Can Be Stored Using a 2-Wire SMBus Serial Interface (Rev 1.1)
• Built-In Safeguards Minimize Misprogramming Due to Bus Conflicts
• Three Open-Drain Pins (CPU_ON, IO_ON, CLK_ON) and a Global Control Pin (VRON) to Shutdown or Soft-Start 3 DC/DC Converters Simul
• PGOOD Pin and 50µs PGOOD Timer
• Available in MSOP-8 and SSOP-16 Package

Typical Application

Description

The LTC1699-80, LTC1699-81 and LTC1699-82 are precision (±0.35% max), digitally programmed resistor dividers that comply with Intel 5-bit mobile (LTC1699-80), desktop VRM8.4 (LTC1699-81) and VRM9.0 (LTC1699-82) VID specifications. Each IC can switch the output of a DC/DC converter between two set voltages. A digital input pin, SEL, selects one of two divider settings stored into registers via a 2-wire SMBus interface.

The SMBus interface uses Write Word protocol to setup the registers and to turn the DC/DC converters on or off. Read Word protocol is used to verify register contents and to return the On/Off status of the converters. The LTC1699-80, LTC1699-81 and LTC1699-82 incorporate safeguards against errors due to bus conflicts.

Three open-drain N-channel outputs (CPU_ON, IO_ON and CLK_ON) are provided to turn DC/DC converter supplies on or off via their RUB/SS inputs. A global control pin, VRON is used to turn the converters on or off simultaneously. An internal timer pulls the PGOOD pin low for 50µs if the divider setting changes or the converters are turned on via the SMBus and the VRON pin.