Philips Semiconductors

Product data

MAX632x/MAX634x

3-pin ultra-low power SC70/SOT

microprocessor reset circuit

2003 Aug 05

8

APPLICATION INFORMATION

Interfacing to

µPs with Bidirectional Reset Pins

The MAX6328/MAX6348 RESET output is open drain and are easily

interfaced with microprocessors which have bidirectional reset pins,

such as the Motorola 68HC11. Directly connecting the

MAX6328/MAX6348 RESET output to the

µPs reset input and

independently assert reset (Figure 7).

GND

GND

RESET

RESET

SL01835

MAX6328/

MAX6348

MOTOROLA

68HCXX

Figure 7. Interfacing to

µPs with Bidirectional Reset Pins

The MAX6326-MAX6348 Series resets are relatively immune to

capability greatly reduces false resets with short-duration pulses.

Figure 8, Maximum Transient Duration versus Reset Comparator

Overdrive, shows the maximum transient condition for which reset

signal are not generated. The graph shows the maximum pulse

width that a negative-going transient may have before it will

generate a reset signal. Note: as the amplitude of the transient

increases, the maximum allowable transient pulse width decreases.

SL01836

0

50

100

150

200

250

300

350

400

450

1

10

100

1000

MAX6326/MAX6327/

MAX6328

MAX6346/MAX6347/

MAX6348

Figure 8. Maximum transient duration without causing a

reset pulse versus reset comparator overdrive.

System configurations with various

µPs

The MAX326-MAX6348 Series resets provide a system solution for

various

µPs. Figures 9 and 10, respectively, reference the Philips

µPs which are compatible with the MAX6326/MAX6346 and

MAX6327/MAX6347 system resets.

GND

GND

RESET

RESET

SL01837

MAX6326/

MAX6346

µP(Note 1)

NOTE:

1. Philips microprocessors with active-LOW resets: All 16-bit

devices from XA-family (XA-Cxx, XA-Gxx, XA-Sxx, XA-Hxx), all

LPC7xx devices (P87LPC760/761/762/767/768/769,

P80C591/P87C591 (with on-chip CAN controller).

Figure 9.

µP System Diagram using MAX6326/MAX6328

Push-Pull, Active-LOW Resets

GND

GND

RESET

RESET

SL01838

MAX6327/

MAX6347

µP(Note 1)

NOTE:

1. Philips microprocessors with active-HIGH resets : 8xC5x, 8xC3x,

8xC5xX2, 8xC3xX2, 8xC51Fx, 8xC51Rx+, 89C51Rx2, 89C66x,

8xC554, 8xC552, etc.

Figure 10.

µP System Diagram using MAX6327/MAX6347

Push-Pull, Active-HIGH Resets