ASM161, ASM162

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3

Part Number

Reset Polarity

ASM161

LOW (use external pull−up resistor)

ASM162

HIGH

Manual Reset

The ASM161/162 have a unique manual reset circuit. A

negative going edge transition on MR initiates the reset. A

manual reset generates a single reset pulse of fixed length.

The output−reset pulse remains asserted for the Reset Active

is completed, the MR input remains disabled for at least

49

mS but not more than 122 mS. This period is specified as

During the MR disabled period, the microcontroller is

guaranteed a time period free of new manual reset signals.

This period can be used to refresh critical DRAM contents

or other system tasks.

The MR pin must be taken HIGH and LOW again after the

pulse.

The manual reset input has an internal 20 k

W pull−up

resistor. MR can be left open if not used.

Figure 3. Manual Reset Timing

Figure 4. RESET Valid with VCC under 1.1 V

Application Information

Glitch Resistance

The ASM161/162 are relatively immune to short duration

negative−going VCC transients/glitches. A VCC transient

that goes 100 mV below the reset threshold and lasts 20s or

less will not typically cause a reset pulse.

Valid Reset with VCC under 1.1 V

To ensure that logic inputs connected to the ASM162

RESET pin are in a known state when VCC is under 1.1 V,

a 100 k

W pull−down resistor at RESET is needed. The value

is not critical.

This scheme does not work with the open−drain outputs

of ASM161.

Table 2. ABSOLUTE MAXIMUM RATINGS

Parameter

Min

Max

Unit

Pin Terminal Voltage with Respect to Ground

RESET, RESET and MR

Input Current at VCC and MR

−0.3

−0.3

6.0

20

V

V

mA

Rate of Rise at VCC

100

V/ms

Power Dissipation (TA = 70°C)

320

mW

Operating Temperature Range

−40

85

°C

Storage Temperature Range

−65

160

°C

Lead Temperature (soldering, 10 sec)

300

°C

ESD rating

HBM

MM

2

200

KV

V

Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the

Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect

device reliability.