Architectural Overview
The Z86D99 is a low-voltage general-purpose one-time programmable (OTP) Z8® microcontroller with an integrated four-channel 8-bit sigma delta analog-to-digital converter. The Z86L99 is the read-only memory (ROM) version of this controller.
   
Features
• Four-channel, 8-bit sigma delta analog-to-digital (A/D) converter with external
    voltage references (not available in the 28-pin configuration)
• Two independent analog comparators
• Controlled current output
• 489 bytes of RAM
    – 233 bytes of general-purpose register-based RAM
    – 256 bytes of RAM mapped into the program memory space that can be
    used as data RAM or executable RAM
• 32 Kbytes of OTP memory (Z86D99X)
• 16 Kbytes of ROM (Z86L99X)

Counter/Timers
• Special architecture to automate generation and reception of complex pulses
    or signals:
    – Programmable 8-bit counter/timer (T8) with two 8-bit capture registers and
    two 8-bit load registers
    – Programmable 16-bit counter/timer (T16) with one 16-bit capture register
    pair and one 16-bit load register pair
    – Programmable input glitch filter for pulse reception
• One general-purpose 8-bit counter/timer (T1) with 6-bit prescaler

Input/Output and Interrupts
• Thirty-two I/Os, twenty-nine of which are bidirectional I/Os with programmable
    resistive pull-up transistors (24 I/Os are available in the 28-pin configuration)
• Sixteen I/Os are selectable as stop-mode recovery sources
• Six interrupt vectors with nine interrupt sources
    – Three external sources
    – Two comparator interrupts
    – Three timer interrupts
    – One low-battery detector flag

Operating Characteristics
• 8-MHz operation
• 3.0 V to 5.5 V operating voltage (Z86D990/Z86D991)
• 2.3 V to 5.5 V operating voltage (Z86L990/Z86L991)
• Low power consumption with three standby modes:
    – Stop
    – Halt
    – Low Voltage Standby
• Low-battery detection flag
• Low-voltage protection circuit (also known as VBO, or voltage brownout,
    circuit)
• Watch-dog timer and power-on reset circuits
  
User-Programmable Option Bits
• Clock source—RC/other (LC, resonator, or crystal)
• Watch-dog timer permanently enable
• 32-kHz crystal
• Port 20–27 pull-up resistive transistor
• Port 40–42 pull-up resistive transistor
• Port 44–47 pull-up resistive transistor
• Port 50–51 pull-up resistive transistor
• Port 54–57 pull-up resistive transistor
• Port 60–63 pull-up resistive transistor (not available in Z86D991/Z86L991)
• Port 64–67 pull-up resistive transistor (not available in Z86D991/Z86L991)
• P43 high impedance in STOP mode (available in OTP only)
    Force P43 to output a 1 in the open-drain configuration