Rainbow-electronics ATmega8HVD Manuel d'utilisateur télécharger pdf (Page 111)

111

8052B–AVR–09/08

ATmega4HVD/8HVD

Notes: 1. The actual value depends on the actual frequency of the ”Ultra Low Power RC Oscillator” on

page 24. See ”Electrical Characteristics” on page 142.

2. Initial value.

3. An additional delay up to T

can be expected after enabling the corresponding FET. This is

related to the initialization of the protection circuitry. For the Discharge Over-Current protec-

tion, this applies when enabling the Discharge FET. For Charge Over-Current protection,

this applies when enabling the Charge FET. With nominal ULP frequency this delay is maxi-

mum 0.2 ms.

Note: Due to synchronization of parameters between clock domains, a guard time of 3 ULP oscillator

cycles + 3 CPU clock cycles is required between each time the BPOCTR register is written. Any

writing to the BPOCTR register during this period will be ignored.

20.8.5 BPSCD – Battery Protection Short-circuit Detection Level Register

• Bits 7:0 – SCDL7:0: Short-circuit Detection Level

These bits sets the R

SENSE

voltage level for detection of Short-circuit in the discharge direction,

as defined in Table 20-4 on page 112. This register should always be written as one-hot.

Note: Due to synchronization of parameters between clock domains, a guard time of 3 ULP oscillator

cycles + 3 CPU clock cycles is required between each time the BPSCD register is written. Any

writing to the BPSCD register during this period will be ignored.

Table 20-3. Over-current Protection Reaction Time. OCPT[5:0] with corresponding Over-

current Delay Time.

Over-current Protection Reaction Time

(1)

OCPT[5:0] Typ

0x00 (0.0 - 0.5 ms) + T

(3)

0x01 (0.0 - 0.5 ms) + T

(3)

0x02

(2)

(0.5 - 1.0 ms) + T

(3)

0x03 (1.0 - 1.5 ms) + T

(3)

... ...

0x3E (30.5 - 31.0 ms) + T

(3)

0x3F (31.0 - 31.5 ms) + T

(3)

Bit 76543210

SCDL[7:0] BPSCD

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value 0 0 0 0 0 0 0 1

1 2 ... 106 107 108 109 110 111 112 113 114 115 116 ... 167 168

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Rainbow-electronics ATmega8HVD Manuel d'utilisateur Page 111

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