PM6685 STMicroelectronics, PM6685 Datasheet - Page 27

• Manufacturer Part Number: PM6685
• Description: IC CTLR DUAL SYNC STDN 5X5VFQFPN
• Manufacturer: STMicroelectronics

Specifications of PM6685

• Applications: Controller, Notebook Power System
• Voltage - Input: 6 ~ 28 V
• Number Of Outputs: 2
• Voltage - Output: -3.3V, 5V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN, 32-VFQFPN
• Output Voltage: 5 V, 3.3 V
• Output Current: 0.1 A
• Input Voltage: 5.5 V to 28 V
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 10 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PM6685
7.9
7.10
Reference voltage and bandgap
The 1.230 V (typ.) internal bandgap voltage is accurate to ±1% over the temperature range.
It is externally available (VREF pin) and can supply up to ±100μA and can be used as a
voltage threshold for the multifunction pins FSEL, SKIP and LDO3_SEL to select the
appropriate working mode. Bypass VREF to ground with a 100nF minimum capacitor.
If VREF goes below 0.87 V (typ.), the system detects a fault condition and all the circuitry is
turned off. A toggle on the input voltage (power on reset) or a toggle on SHDN pin is
necessary to restart the device.
An internal divider of the bandgap provides a voltage reference Vr of 0.9 V. This voltage is
used as reference for the linear and the switching regulators outputs. The overvoltage
protection, the undervoltage protection and the power good signals are referred to Vr.
Internal linear regulators
The PM6685 has two linear regulators providing respectively 5 V(LDO5) and 3.3 V(LDO3) at
±2% accuracy. High side drivers, low side drivers and most of internal circuitry are supplied
by LDO5 output through VCC pin (an external RC filter may be applied between LDO5 and
VCC). Both linear regulators can provide an average output current of 50 mA and a peak
output current of 100 mA. Bypass both LDO5 and LDO3 outputs with a minimum 1 μF
ceramic capacitor and a 4,7 μF tantalum capacitor (ESR < 2 Ω). If the 5 V output goes below
4V, the system detects a fault condition and all the circuitry is turned off. A power on reset or
a toggle on SHDN pin is necessary to restart the device.
V5SW pin allows to keep the 5 V linear regulator always active or to enable the internal
bootstrap-switch over function: if the 5 V switching output is connected to V5SW, when the
voltage on V5SW pin is above 4.8 V, an internal 3.0 Ω max p-channel MOSFET switch
connects V5SW pin to LDO5 pin and simultaneously LDO5 shuts down. This configuration
allows to achieve higher efficiency. V5SW can be connected also to an external 5 V supply.
LDO5 regulator turns off and LDO5 is supplied externally. If V5SW is connected to ground,
the internal 5 V regulator is always on and supplies LDO5 output.
Table 7.
The 3.3 V linear regulator is supplied by LDO5 output.
LDO3_SEL pin allows to keep 3.3 V linear regulator always enabled, always disabled or to
enable the internal bootstrap-switch over function. According to
●
Switching 5V
External 5V
If LDO3_SEL is connected to VREF pin, when the power good signal of the 3.3 V
switching output voltage PGOOD3(see related sections) is high, the internal linear
V5SW
supply
output
GND
V5SW multifunction pin
The 5V linear regulator is always turned on and supplies LDO5 output.
The 5V linear regulator is turned off when the voltage on V5SW is above 4.8V
and LDO5 output is supplied by the switching 5V output.
The 5V linear regulator is turned off when the voltage on V5SW is above 4.8V
and LDO5 output is supplied by the external 5V.
Doc ID 11674 Rev 8
Description
Table 7
:
Device description
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