M58LR128HT datasheet(14/112 Pages) STMICROELECTRONICS

14 / 112 page

Signal descriptions

M58LR128HT, M58LR128HB

14/112

2.13

VPP Program supply voltage

VPP is both a control input and a power supply pin. The two functions are selected by the

voltage range applied to the pin.

If VPP is kept in a low voltage range (0V to VDDQ) VPP is seen as a control input. In this case

a voltage lower than VPPLK gives absolute protection against program or erase, while VPP in

the VPP1 range enables these functions (see Tables 21 and 22, DC Characteristics for the

relevant values). VPP is only sampled at the beginning of a program or erase; a change in its

value after the operation has started does not have any effect and program or erase

operations continue.

If VPP is in the range of VPPH it acts as a power supply pin. In this condition VPP must be

stable until the Program/Erase algorithm is completed.

2.14

VSS ground

VSS ground is the reference for the core supply. It must be connected to the system ground.

2.15

VSSQ ground

VSSQ ground is the reference for the input/output circuitry driven by VDDQ. VSSQ must be

connected to VSS

Note:

Each device in a system should have VDD, VDDQ and VPP decoupled with a 0.1 µF ceramic

capacitor close to the pin (high frequency, inherently low inductance capacitors should be as

close as possible to the package). See Figure 8: AC measurement load circuit. The PCB

track widths should be sufficient to carry the required VPP program and erase currents.

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