SH3003 Datasheet, PDF (7/30 Pages) Semtech Corporation – MicroBuddy® Support IC for Microcontrollers

SH3003
POWER MANAGEMENT
Pin Descriptions (continued)
Pin Pin Name
Type
Pin Function
9
RREF
Analog
Optional 1MΩ external bias resistor for internal 32.768 kHz RC oscillator. Can
be used to set, trim or modulate the internal RC oscillator. Keep open if not
used.
Active low system reset output. Asserted with a strong low state when a reset
10
NRST
Digital Out condition occurs. Weakly pulled to VDD internally when not active. This signal is
valid for VDD as low as 1V. Keep open if not used.
Active high system reset output. Asserted with a strong high state when a reset
11
RST
Digital Out condition occurs. Weakly pulled to VSS internally when not active. This signal is
valid for VDD as low as 1 V. Keep open if not used.
12 TEST (VSS) Digital In Factory test enable. All VSS pins & TEST (VSS) pin must be connected together.
Buffered internal 32.768 kHz clock, derived according to the CLKSEL pin setting.
Pin uses backup power for the buffer when VDD is not present. When driving
13
CLK32
Digital Out
high, this signal is either at VBAK or VDD (if VDD is higher than the reset threshold).
When enabled, this signal runs continuously independent of CLKOUT activity.
Minimize the external load to reduce power consumption during backup opera-
tions. When disabled, this pin is driven to VSS. Keep open if not used.
14
IO/INT
Serial communications interface and interrupt output pin. Pin is internally weakly
I/O
pulled to opposite of programmed interrupt polarity. If interrupt is programmed to
be active low, pin is weakly pulled to VDD when inactive. Keep open if not used.
15
CLKIN
Digital In
Clock activity sense input. Detects when target microcontroller enters stop mode
(which disables its clock). Connect to the microcontroller’s clock output or oscil-
lator output pin. Connect to VSS when not used. CLKIN must not be left open.
16
CLKOUT
Digital Out
Programmable high frequency clock output. Connect to the target microcon-
troller’s clock input or oscillator input pin. Keep open if not used.
T
Thermal Pad
Pad for heatsinking purposes. Connect to ground plane using multiple vias. Not
connected internally.
©2006 Semtech Corp.
7
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