I’ve been learning how to repair Dell laptops for the past two weeks. I previously wrote about the DC power supply input circuit and listed all the components I found, including MOSFETs like SI7121DN and FDV301N, as well as various capacitors and resistors.
At the time, I didn’t mention it, but I want to record now that I did not see any inductors in the schematic. I’ve watched several laptop repair videos on YouTube, and they often mention inductors as an important part of the DC input power section. However, in this Dell Inspiron laptop, I couldn’t find any inductor in the DC input circuit on Page 32 of the Dell laptop schematic. The download link for this schematic is at the end of this diary note.
While studying the DC input circuit, I followed the signal labels shown on the schematic and discovered that they connect to the NPCE885PA0DX I/O controller chip. That led me to ask: how laptops and PCs start up?
The Intel PCH Panther Point BGA989 HM77 refers to a specific chipset from Intel's Panther Point series, designed for laptops and mobile platforms. Here's a breakdown of its key aspects:
1. Intel Panther Point (7-Series Chipsets)
- Part of Intel's 7-Series chipsets (codenamed Panther Point), released alongside Ivy Bridge (3rd Gen Core) processors in 2012.
- Designed to work with Socket G2 (rPGA988B/BGA1023) CPU.
2. HM77 Chipset
HM77 is a mobile-oriented chipset in the Panther Point family, intended for mainstream laptops
- Key features:
- Supports Intel Rapid Storage Technology (RST) for RAID 0/1/5/10.
- USB 3.0 support (up to 4 ports via integrated controller).
- PCIe 2.0 lanes for connectivity.
- Supports Intel Smart Response Technology (SSD caching).
- No overclocking support (unlike the HM76, which had limited OC features in some laptops).
3. BGA989 Package
- BGA989 refers to the Ball Grid Array packaging with 989 pins.
- This means the chipset is soldered directly to the motherboard (common in laptops).
- Not user-replaceable.
4. Typical Usage
- Found in 2012-2013 business and consumer laptops(e.g., Lenovo ThinkPad T430, Dell Latitude E6430, HP EliteBook 8470p).
- Paired with Ivy Bridge CPUs like the Core i5-3320M, i7-3520M, etc.
5. Alternatives in Panther Point
- QM77 (for business laptops with vPro support).
- UM77 (ultra-low-power for ultrabooks).
- HM76 (similar to HM77 but with fewer features).
- HM75 (no RAID or Smart Response support).
In a Dell laptop with an Intel PCH Panther Point HM77 (BGA989) connected to a 17W Ivy Bridge/Sandy Bridge CPU, the connection between the CPU and the PCH (Platform Controller Hub) is established via Intel's Direct Media Interface (DMI). Below is block diagram showing the connection between the Intel CPU and the PCH.
Here’s a detailed breakdown:
1. CPU ↔ PCH Connection: DMI (Direct Media Interface)
- DMI Version: DMI 2.0 (since HM77 is a 7-Series chipset).
- Function: Acts as the primary high-speed interconnect between the CPU and PCH.
- Bandwidth: 2 GB/s (x4 PCIe 2.0 equivalent).
- Purpose: Handles all communication between the CPU and peripherals (USB, SATA, PCIe, etc.).
2. Key Connections from HM77 PCH to Other Components
The HM77 PCH manages most I/O functions, while the CPU handles memory and graphics. Here’s how the PCH connects to different components:
A. Storage (SATA)
- SATA Ports:
- 2x SATA 6Gbps (for SSDs/HDDs).
- 1x mSATA (SATA 3Gbps) (common in ultrabooks for caching SSDs).
- Intel Rapid Storage Technology (RST) supported (RAID 0/1/5/10).
B. USB
- 4x USB 3.0 ports (via integrated controller).
- 8x USB 2.0 ports (shared with internal devices like webcam, Bluetooth, etc.).
C. PCI Express (PCIe)
- 8x PCIe 2.0 lanes (for Wi-Fi, Ethernet, Thunderbolt (if supported), etc.).
- Not for the dGPU: The discrete GPU (if present) connects directly to the CPU via PCIe 3.0 x16.
D. Networking
- Gigabit Ethernet (via PCIe or PCH-integrated LAN).
- Wi-Fi/Bluetooth (typically connected via PCIe or USB).
E. Audio (Intel HD Audio)
- HDA (High Definition Audio) link** for speakers/microphone.
- Codec chip** (e.g., Realtek ALC3204) connects to PCH.
F. Display (via CPU, not PCH)
- Integrated GPU (Intel HD 3000/4000)** is inside the CPU.
- LVDS/eDP: For internal laptop display.
- HDMI/DP: External display outputs (handled by CPU, not PCH).
G. LPC (Low Pin Count) Bus
- Connects to:
- BIOS/UEFI Flash Chip (SPI).
- EC (Embedded Controller) also called I/O controller or Keyboard Controller
- TPM (Trusted Platform Module) if present.
3. Power & Thermal Considerations (17W CPU)
- 17W TDP CPUs (e.g., i5-3317U, i7-3667U) are ultra-low-power Ivy Bridge chips.
- HM77 PCH power draw: ~3-4W (managed via laptop power delivery).
- Shared cooling: Some Dell laptops use a shared heat pipe for CPU + PCH.
4. Example Dell Laptops Using HM77 + 17W Ivy Bridge
- Dell Latitude 6430U (i5-3427U, HM77).
- Dell XPS 13 (2012) (i7-3517U, HM77).
- Dell Inspiron 14z (i5-3317U, HM77).
The HM77 PCHconnects to the 17W Ivy Bridge CPU via DMI 2.0, acting as the central hub for storage, USB, networking, and low-speed peripherals. The CPU handles graphics, memory, and high-speed PCIe devices (like a dGPU). This setup was common in Dell ultrabooks and business laptops from 2012-2013. i875. The Intel HM77 (Panther Point, BGA989) is a mobile chipset for Ivy Bridge-based laptops, offering USB 3.0, RAID, and SSD caching support. It was widely used in mid-range to high-end notebooks before being succeeded by 8-Series chipsets (Haswell era).
