P89LPC938 NXP Semiconductors, P89LPC938 Datasheet - Page 31

• Manufacturer Part Number: P89LPC938
• Description: The P89LPC938 is a single-chip microcontroller, available in low cost packages, based ona high performance processor architecture that executes instructions in two to four clocks,six times the rate of standard 80C51 devices
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 14051
Product data sheet
7.19.7 Alternating output mode
7.19.8 PLL operation
In asymmetrical mode, the user can set up PWM channels A/B and C/D as alternating
pairs for bridge drive control. In this mode the output of these PWM channels are
alternately gated on every counter cycle.
The PWM module features a Phase Locked Loop that can be used to generate a
CCUCLK frequency between 16 MHz and 32 MHz. At this frequency the PWM module
provides ultrasonic PWM frequency with 10-bit resolution provided that the crystal
frequency is 1 MHz or higher. The PLL is fed an input signal of 0.5 - 1 MHz and generates
an output signal of 32 times the input frequency. This signal is used to clock the timer. The
user will have to set a divider that scales PCLK by a factor of 1-16. This divider is found in
the SFR register TCR21. The PLL frequency can be expressed as shown in
Where: N is the value of PLLDV3:0.
Since N ranges in 0 - 15, the CCLK frequency can be in the range of PCLK to
PLL frequency
Fig 10. Alternate output mode.
=
----------------- -
PLCK
N
+
Rev. 01 — 25 February 2005
1
8-bit microcontroller with 10-bit A/D converter
002aaa895
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
TOR2
COMPARE VALUE A (or C)
COMPARE VALUE B (or D)
0
PWM OUTPUT A (or C) (P2.6)
PWM OUTPUT B (or D) (P1.6)
TIMER VALUE
P89LPC938
Equation
PCLK
31 of 68
16
.
1.
(1)