MAX7378 Datasheet, PDF (6/10 Pages) Maxim Integrated Products – Silicon Oscillator with Low-Power Frequency Switching and Reset Output

Silicon Oscillator with Low-Power
Frequency Switching and Reset Output
Typical Operating Characteristics (continued)
(V_CC = V_L = 5V, T_A = +25°C, unless otherwise noted.)
LOW-SPEED TO HIGH-SPEED
TRANSITION
MAX7378 toc19
LOW-SPEED TO HIGH-SPEED TRANSITION
(EXPANDED SCALE)
MAX7378 toc20
CLOCK
CLOCK
SPEED
SPEED
20µs/div
400µs/div
Pin Description
PIN
NAME
FUNCTION
1
V_CC
Positive Supply Voltage. Bypass V_CC to GND with a 0.1µF capacitor.
2
V_L
Output Supply Voltage. Connect V_L to V_CC. Bypass V_L to GND with a 0.1µF capacitor.
3
SPEED ^{Clock Speed-Select Input. Drive SPEED low to select the 32kHz fixed frequency. Drive SPEED high to}
select factory-trimmed frequency.
4
RST
Reset Output. See the RST Reset Output Options section for more details.
5
CLOCK Push-Pull Clock Output
6
GND
Ground
7
ENABLE Active-High Clock Enable Input. See the ENABLE Input section for more details.
8
N. C.
No Connect. No internal connection.
Detailed Description
The MAX7378 is a dual-speed clock generator with
integrated reset for microcontrollers and UARTs in 3V,
3.3V, and 5V applications (Figure 1). The MAX7378 is a
replacement for two crystal-oscillator modules, crystals,
or ceramic resonators and a system-reset IC. The high-
speed clock frequency is factory trimmed to specific
values. A variety of popular standard frequencies are
available (Table 2). The low-speed clock frequency is
fixed at 32.768kHz (Figure 1). No external components
are required for setting or adjusting the frequency.
Supply Voltage
The MAX7378 has been designed for use in systems
with nominal supply voltages of 3V, 3.3V, or 5V and is
specified for operation with supply voltages in the 2.7V
to 5.5V range. See the Absolute Maximum Ratings sec-
tion for limit values of power-supply and pin voltages.
Oscillator
The clock output is a push-pull configuration and is
capable of driving a ground-connected 500Ω or a posi-
tive-supply connected 250Ω load to within 400mV of
either supply rail. The clock output remains stable over
the full operating voltage range and does not generate
short output cycles when switching between high- and
low-speed modes. A typical startup characteristic is
shown in the Typical Operating Characteristics.
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