UPD720122 datasheet(56/82 Pages) NEC

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Data Sheet S16685EJ2V0DS

µPD720122

(2) External local bus 8-bit mode

(a) External local bus 8-bit mode DMA single mode read transfer timing

Symbol

Parameter

Min.

Typ.

Max.

Unit

L8T21

DMA request acknowledge setup time (EP1_RDB

↓)

∞

L8T22

DMA request off time 1 (EP1_DACKB

↓)

−

L8T23

DMA single mode read transfer cycle time

∞

L8T24

Read command width

∞

L8T25

Read command inactive time

∞

L8T26

Read data delay time (EP1_RDB

↓)

−

L8T27

Buffer direction change time (EP1_RDB

↓)

−

L8T28

Read data hold time (EP1_RDB

↑)

−

L8T31

EP1_STOPB delay time (EP1_RDB

↓)

−

L8T32

EP1_STOPB delay time (EP1_RDB

↑)

−

L8T33

DMA request acknowledge hold time (EP1_RDB

↑)

∞

L8T34

Undefined

−−

Remarks 1.

Use of EP1_TCB is prohibited in the 8-bit external local bus mode. Clamp this signal to the inactive

status.

LD15 to 8 are undefined in the 8-bit external local bus mode (these signals are invalid when input and

undefined when output).

It is assumed that the external pin capacitance is 15 pF (data bus = 50 pF).

(Overall)

EP1_DRQB

EP1_TCB

LD7 to LD0

EP1_RDB

EP1_DACKB

N cycle

−−−− 1 cycle

1 cycle

L8t22

L8t23

L8t24

L8t25

L8t26

L8t28

High level

EP1_STOPB

High level

EP1_STOPB is not asserted in

the case of a full packet.

L8t21

L8t27

L8t31

L8t32

L8t33

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